WEBVTT

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Now the past, by a virtue
of being passed, remains forever inaccessible to

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us. It is no more we
cannot reach it. It is only from

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its traces and remains from its debris, which are still present works of art,

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monuments, documents which have escaped the
ravages of time and mankind, that

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we attempt to construct it. But
objective history, the history men make and

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suffer, is not concerned or hardly
with the history of historians. It allows

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the survival of things of no value
to the historian mercilessly destroys the most important

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of documents, the most beautiful of
works, the most impressive monuments. What

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it leaves or has left behind are
mere fragments of what we should need.

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Accordingly, historical reconstructions are inevitably fragmentary, uncertain, and even doubly uncertain.

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En Alexandre Corre, nineteen sixty one. Our knowledge of Galileo's life is derived

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essentially from three sources. One is
Vincenzo Ivanni, who was his last student.

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He wrote Galileo's first biography, not
published until seventeen seventeen, about fourteen

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years after Viviani had died, When
he passed his personal papers became the property

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of his nephew, and then to
the nephews of his nephew. How they

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ended up becoming discovered for what they
were is a bit of a tail in

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and of itself, you see.
One day in the spring of seventeen fifty,

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Giovanni Battista Neely, a man of
Florence of letters, made a detour

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to buy some cold meat from a
butcher he normally did not frequent when out

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in the countryside with his friends.
He unwrapped the meat, he noticed that

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the waste paper it was wrapped in
appeared to be something written by Galileo.

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Returning with all possible haste to the
butcher, but taking the precaution of concealing

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his discovery from his friends, he
eventually traced the butcher's waste paper to its

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source, a large bin overflowing with
documents in Viviani's old house. His grand

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nephews were selling off the paper in
small parcels as wrapping paper, but we're

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happy to sell the whole bin to
Nelli. Nelly used his treasure trove to

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write a life of Galileo, and
the papers he acquired eventually ended up in

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the Florentine archives. There they were
used by the greatest of all Galileo's scholars,

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Antonio Favarro, who produced what is
known as the National edition of Galileo's

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work around the year nineteen hundred,
printed in twenty volumes. By the way,

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Favarro was meticulous, and almost everything
about Galileo that we know today Favarro

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knew over one hundred years ago.
But Favarro was not an impartial scholar,

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I mean no one is. He
labored to defend Galileo's reputation as a scientist,

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as a man, and as a
pious Catholic. Inconvenient details he buried,

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he brushed them aside, or just
shows to change them to the best

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possible light. They were never two. Favado's credit suppressed completely when Galileo died

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in sixteen forty two. He had
been living in Florence for more than thirty

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years, accumulating letters and papers.
But when he moved from Padua to Florence

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in sixteen ten at the age of
forty six, he must have packed his

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clothes, books, papers, telescopes
and lens grinding machinery to be loaded under

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the backs of donkeys or mules,
and presumably me threw a lot of things

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away, as we all do when
we move right. In Fravado's edition of

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the o Peire, the letters to, from, and about Galileo occupy nine

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of the twenty volumes. One of
these, volume ten, contains all the

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letters for the first forty six years
of his life. Another volume, fifteen,

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contains letters for just a single year, sixteen thirty three, the year,

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as we'll see of Galileo's inquisition trial. The imbalance is frustrating, of

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course, in that Galileo made no
major scientific discoveries after the age of fifty,

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and yet the bulk of the evidence
that survives come from the last decades

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of his life. In addition,
when Galileo went blind in sixteen thirty seven,

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he lost control over his own papers. Things he would have once thrown

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away were now faithfully kept. Now, thanks to those three men, Vivanne,

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Nelly and Favarro, we know a
great deal about Galileo, and it's

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frankly easy to be overwhelmed by the
bulk of this knowledge. Remember, one

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volume of a twenty volume set is
just letters from one year. It's also

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easy to forget that most of our
important source consists of an old bin full

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of papers. We have no way
of knowing how many documents had already been

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extracted from the bin and used to
wrap various lunch meets. Unfortunately, it's

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not our only problem. All the
documents in the bin had first been sifted

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through by Viviani. From Galileo's death
until his own death in seventeen oh three,

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Viviani was engaged in a campaign to
restore his master's reputation, blated,

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of course, by the Inquisition's condemnation
of him in sixteen thirty three. He

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wanted to see Galileo given a proper
burial under a tomb worthy of his status

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as a great scientist. He wanted
to see his works, including his scientific

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correspondence published. Because he could achieve
neither of those objectives, he turned the

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facade of his own house into a
monument to Galileo, recording at length and

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in stone all his scientific achievements,
but making no mention of either Copernicanism or

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of the Inquisition trial and the condemnation. An essential element in Viviani's campaign to

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recuperate Galileo's reputation was his insistence that
Galileo was a good Catholic. Galileo was

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portrayed by Viviani as dismayed by the
publication of his works abroad after sixteen thirty

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three, in direct defiance, as
we'll see of the inquisition, the evidence

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to the contrary, which was and
remains incontrovertible, Viviani quietly suppressed. It

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has been suggested that Viviani genuinely believed
that Galileo's Copernicanism represented a tragic intellectual error.

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Yet the evidence rather suggests that,
as Galileo's faithful disciple, he skillfully

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combined outward conformity to the requirements of
the Church with private dissent. Now,

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how far did Viviani's single minded preoccupation
with Galileo's reputation lead him to falsify historic

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record? That he falsified to some
degree, I think every single historian I

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have read suggests is one hundred percent
true. He planned to publish an exchange

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of letters between Galileo and Genevan by
the name of ele do Yo Tati,

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a Genevan who was nominally a Protestant
but had some close relations the number of

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unbelievers on the subject of measuring longitude, telling the Atati that he would alter

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or omit some sentences that might provoke
hostility to Galileo and make it difficult to

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obtain a license to publish. But
what did he plan to leave out?

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And this is just an example of
what we don't know. Viviani separated out

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thirteen letters on longitude so that they
survived to be published in seventeen eighteen,

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at which point they were destroyed.
We cannot tell how extensively they would have

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been revised Viviani had been able to
publish them, although there is another case

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in which we can a little bit
see Viviani's hand rewriting a letter in order

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to protect Galileo's reputation. Viviani had
in his possession. So far as we

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can tell, around one hundred letters
between Galileo and Diatatdi, but yet none

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of these survive. Forty are completely
lost. The rest are preserved only in

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partial copies made by Viviani, or, in the addition of seventeen eighteen,

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or in two cases, copies made
by a third party. Of course,

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it's theoretically possible that every one of
the letters that did not survive until seven

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eighteen went to wrap lunch meets.
But I think what's much more likely,

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and what most historians seem to agree
is that these letters were probably destroyed by

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Viviani himself, mostly because they contained
proof that Galileo had continued to advocate for

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Copernicanism after sixteen thirty three. Of
course, the charge is a serious one.

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I Viviani was prepared to falsify the
record, then we must assume that

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he destroyed any evidence which cast out
on Galileo's Catholic piety. On the twenty

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fourth of July sixteen seventy three,
he wrote to a scientist and diplomat in

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Flanders saying that he had heard an
edition of Paolo Sarpi's letters which were soon

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to be published in Amsterdam, and
that there might be some letters between Galileo

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and sarp in this anthology. Now, of course, sarp who had been

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a close friend of Galileo's, was
actually notorious throughout Europe as the author of

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the quote History of the Council of
Trent, widely regarded as the most effective

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piece of anti Catholic propaganda to have
been published since the days of Lutheran Calvin.

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The publication of such a correspondence,
even if it only concerned scientific matters,

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would Vianni felt be fatal to Galileo's
reputation. Viviani went to great lengths

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after this to try to prevent the
publications of these letters, even though ultimately

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he was not successful. I think
this story is important because it represents a

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cautionary tale about reconstructing history before the
modern age. We simply do not have

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all of the documents that passed into
Viviani's hands. We have some of them,

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but doubtless many were lost and many
others deliberately destroyed in order to try

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to portray Galileo as a Catholic piety. Hence, we need to be comfortable

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with some gaps in our understanding and
knowledge. I will, when possible,

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try to fill in some holes with
some basic inferences, but I will of

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course concede that those are inferences and
not hard facts, and I will delineate

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those when they occur. So getting
to Galileo, the story, of course,

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begins with his birth. Galileo's father, Vincenzo, was a musician from

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the Italian city of Florence. In
fifteen sixty two. We get our first

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mention of Vincenzo in any surviving public
record when he shows up in the city

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of Pisa and founds a music school. He married in the July of fifteen

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sixty two. Galileo, his oldest
child, was born on February the fifteenth,

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fifteen sixty four. We know that
Vincenzo received a portion of his wife's

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dowry and silk, leading historians to
conclude that he married into a family of

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cloth merchants. Galileo himself was originally
intended for the wool business. That plan

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would of course, never come to
pass. Later in life, Galileo would

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complain that he never received anything of
value from his father, quite the scathing

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criticism. And we do not know, of course, much about the lives

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of young people in general during the
pre modern period, and Galileo is not

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an exception to that rule. But
we do know from old stories that he

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developed an appreciation early on for working
with his hands. He would spend hours

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building models and other trinkets. This
scale would serve him well later in life.

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In fact, for twenty years,
Galileo had the best telescopes in Europe

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because he built them himself. Other
astronomers had to buy lenses and try to

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just kind of jimmy rig them in
the contraption. Now, the young Galileo

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would have got the finest education available
during that time for someone of his class,

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consisting of course of Latin, Greek
and Aristaeleian logic. He began school

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in Pisa, but moved to Florence
when he was ten. For a brief

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moment, we know that Galileo considered
entering the seminary. This was when he

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was around fourteen years old, but
his father had more mundane plans for his

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son and would not allow it.
History and science will thank him for that.

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At the age of sixteen, Vincenzo
was now determined to send his son

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to university. The plan was for
him to become a doctor. Despite the

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fact that Galileo claimed his father never
gave him anything, he did at least

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implicitly get something from him. Vincenzo
was an early proponent of what we would

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call music theory today. He wrote
an important book on the subject, titled

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Dialogue on Ancient and Modern Music in
fifteen eighty one, and crucially, he

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wrote in Italian, not Latin,
which would inspire Galileo to do the same

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later. Critically, if we're kind
of looking for some parallels between Vincenzo and

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his son, Galileo, Vincenzo also
conducted a series of experiments on strings and

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their influence on the sound that was
produced. How much of these experiments Galleo

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witnessed we can't be sure. With
given Galileo's later emphasis on experimental analysis,

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I think it's safe to say he
picked up some of what his father was

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putting it down. Galleo would forever
remain a musician's son. Later, when

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describing reform, he would compare any
sort of change to tuning an organ.

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Perhaps the elder Vincenzo did symbolize failure
to his son, he certainly presented him

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with a model of forwarded ambition.
Vincenzo always saw himself as a great man,

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for who all his modest success at
court had never been given his due.

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Galileo's refus usual to submit to censorship, to sync back into anonymity may

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be interpreted as a refusal to relive
his father's failed life. But Vincenzo's most

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significant example to his son definitely lay
elsewhere, and I already mentioned it.

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The culture of late sixteenth century Italy
was one obsessed with the imitation of ancients

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and classics, in philosophy, in
medicine, in law, and sculpture,

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the ancient models were still the ones
to follow. Of course, in music

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the situation was always more complicated.
Vincenzo accepted the current view that ancient music

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was monadic while modern music was polyphonic. Ancient music, he thought, spoke

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directly to the soul and was far
superior to anything produced by the moderns.

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But while he experimented with a different
number of ancient compositions, none survive,

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but they're thought to have been sort
of precursors to opera. For the most

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part, Vincenzo always wrote in what
we would call modern music, it might

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be thought that the idea of progress
is sort of anachronistic, as we might

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apply it to the world of Galileo's
youth. Certainly, as we've discussed on

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this podcast several times over the past
couple weeks, the notion of progress is

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something that was just totally foreign to
early modern Europe, certainly outside the fields

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of painting and mathematics. The idea
of progress, of growth, of change

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all being positive things, I mean, that was tenuous at best in the

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sixteenth century. Yet, despite placing
himself firmly on the side of progress,

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which he's going to do Galileo's ultimate
fate would be sadly to repeat what his

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father had done. Vincenzo Galileo rejected
the Pythagorean notion of a harmony that ran

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through the cosmos and implied that there
could be no music of the spheres.

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Sounds are the imperfect products of particular
physical objects. His son was to end

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up destroying the natural correspondences that were
supposed to exist between the microcosm, that

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is, the little world of humankind
and the macrocosm, the divinely ordained universe,

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and he was to remap the cosmos
so that heaven and Hell could no

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longer be located in a physical space. He was to leave many of his

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readers longing for a past that was
no longer attainable, just like those who

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read Vincenzo likely felt. Galileo was
born in Pisa, spent much of his

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childhood there, went to university there, and got his first real job there.

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But Viviani always thought it was important
to stress that Galileo was a Florentine

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gentleman who just happened to spend a
few years in Pisa and mary there.

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Throughout his life. Galileo did the
same always referring to himself as a man

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of Florence. Italians frequently identified people
from the towns that they came from,

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for example, Leonardo da Vinci from
Vinci Pierto, Perugio and the piece Ins

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and some others too still naturally call
Galileo Galileo il Pisano, but this would

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not have made Galileo happy. Pisa
at this point in the seventeenth century was

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a sleepy backwater. Sure, it
had once been a free and independent city,

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a bustling port on the River Arno, but now the population had declined

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to the point where there were hardly
ten thousand people left. The streets were

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half empty, and the university only
had a local reputation. Florence, on

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the other hand, was the capital
of Tuscany. It had a population of

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eighty thousand. That's where power was
concentrated and fashion were set. Galileo inherited

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his father's conviction that Florence was and
would always be his true home. He

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went back to Pisa as a student, to the world of his mother's family,

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with no sense that he was going
home. In the university register,

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he entered his name as Florentinas,
which means from Florence, not Pisa,

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on us from Pisa. In later
years, it was commonly assumed that he

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had been born and raised in Florence, but there was some gossip to the

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contrary. An enemy denouncing him to
the Inquisition said that he represented himself as

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a Florentine, but that he was
in fact a piece in Galileo remained an

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inhabitant of a very small part of
northern Italy throughout his entire life. Honestly,

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really small. If you just take
out a map right now in a

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compass and draw a circle with Florence
at the center and with a radius of

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about two hundred and seventy five kilometers
or one hundred and seventy miles, Galleo

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never once in his life stepped outside
that circle. Genoa population sixty thousand to

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the north and west, Venice one
hundred and fifty thousand people to the east,

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and Rome one hundred and ten thousand
to the south marked the limits of

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his travels. In a telling phrase, he once described someone who had been

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to Genoa, Rome and Milan as
having seen the world. His brother would

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go much farther. He went to
Poland in search of work as a musician,

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Galleo stayed close to home. It's
true that he talked of traveling further

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to Naples, even Spain, and
when he did he always looked south,

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not north. The books he wrote
made the long journey across the Alps,

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but Galleo the man never did.
In Padua, he taught students from across

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Europe, but as far as we
know, he never went to visit any

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of them. Europe in general had
changed a lot during Galleo's life. We're

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going to get into this much more
in the next few weeks, but overall,

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power and wealth was in the process
of shifting permanently in Europe, from

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south to north, from Catholic to
Protestant. The world of Europe, dominated

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by Mediterranean cultures was going away,
and it was permanently fading. Not that

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anybody knew that at the time.
For example, when he was four years

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old, the Dutch revolt against Spain
began. Six years after he died,

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the Dutch got their independence. Now. Interestingly, though at least based on

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what survives, it seems that Galileo
had very little interest in European politics.

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He was, though more modern than
many of his contemporaries. He only wrote

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one book in Latin, The Starry
Messenger. Everything else he wrote in the

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vernacular today we anagronistically call that language
Italian. Galleo wrote in the name tongue

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of Florence, though though his books
traveled widely, even as far away as

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Russia. Sadly, we know far
too little about Galileo's intellectual development between fifteen

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eighty one, when he was a
university student and sixteen ten, when he

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became famous. Frankly, most of
what gets written in secondary histories and biographies

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that try to recount this period of
his life is purely or at least mostly

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conjectural. There's really a double process
that's going on during this time period.

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First, there is definitely the invention
of a new physics, a physics which

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will ultimately be codified by Newton.
Galileo develops an idea of inertia, discovers

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the law of acceleration of falling bodies, the parabolic path of a projectile,

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and the principle of a pendulum,
the principle that every pendulum keeps time and

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that any two pendulums at the same
length keep the same time, and he

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formulates for the first time the idea
that motion is a relative complex. These

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five innovations, taken together, constitute
the most important development in science between Aristotle

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and Newton, or, in the
words of a contemporary of Galileos, the

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most important advance in philosophy for two
thousand years. Now. Second, there's

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also a crucial advance in this time
period in the experimental method. Galleo did

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not invent the experimental method, and
his commitment to it was limited. Nevertheless,

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he definitely put it to more effective
use than anyone had ever done previously,

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and it was his students who became
the most effective proponents for an experimental

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science. Now, the problem with
kind of looking at this process from a

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macro level is that it's very easy
for us today to underestimate the obstacles that

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stood in the way of these two
key developments. It's perfectly possible to carry

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out experiments without having any grasp of
the power of the experimental method. It's

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equally possible to discover one or another
element of the new physics, the parabolic

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path of a projectile, for example, without having any grasp of the full

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range of interlocking arguments that became apparent
to Galileo by sixteen ten. Thus,

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if we are to do justice to
Galileo and Galileo's achievement, we have to

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see that he advanced step by step, really without knowing where he was going.

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Only at the very end could he
look back and recognize that what he

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had done was construct a new side. Ants now we know this. In

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fifteen eighty one, Galileo went to
university to study medicine. This meant learning

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math and even a little astronomy.
Okay, well, really astrology. Reading

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a patient's horoscope was one hundred percent
part of one's medical practice in the sixteenth

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and seventeenth centuries, so knowing what
the stars were saying very important. Again,

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according to Viviani, Galileo made an
important discovery even before he really started

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to study mathematics. One day,
when he was attending a service in the

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cathedral, he noticed a lamp dangling
from a long chain. It had recently

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been lit, and as a result, it was swinging slowly back and forth.

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Counting the length of each swing against
his pulse or against the beat of

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the liturgical music, he realized that
even though the arc of each swing was

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shorter than the one before, re
swing took the same amount of time.

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Viviani says that He went on to
confirm this by experiment. Galileo thus had

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now discovered an accurate way of counting
time before the invention of the pendulum clock.

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As an aside, clocks were driven
by weights and were far from accurate.

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Now. Initially as a medical student, he even used a pendulum,

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really, I think, for the
first time that we know of, to

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measure the pulse rate of patients,
thus immediately taking a theoretic concept and giving

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it a practical application. Sadly,
though Viviani's story about the pendulum has long

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been dismissed as a myth, there
is no evidence at all for Galileo's interest

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in pendulums until about twenty years later. Frankly, we'll probably never know if

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the young Galileo sought to measure the
duration of a pendulum swing. Being said,

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I'm not going to say it didn't
happen. It's certainly possible given his

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later interest in motion. But again, it's one of the problems that we

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deal with here in the early modern
period when we're going off of secondary histories

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such as Viviani's. After three and
a half years of studying medicine in Pisa,

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Galileo returned to Florence in fifteen eighty
five to study mathematics. At this

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point, he was clearly no longer
parroting what his father wanted to hear.

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Galleo had, for better or worse, decided to be his own person.

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It's interestingly also during this time period
that Galileo's love of an interest in Archimedes,

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the Greek mathematician and scientists of the
third century BCE, became apparent,

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and it would be so for the
rest of Galleo's life. In fact,

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Galleo's later love of Archimedes would prove
to be a bit of an impediment for

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00:29:00.279 --> 00:29:06.200
the man first and often cited as
the real Western scientist. For all his

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genius, Archimedes was never a scientist
in the modern sense of the word,

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because he didn't conduct experiments Galileo will. That's what sets Galleo apart, and

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that tension is evident at this point
Galileo's life until the moment he dies.

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Galileo's relationship to Archimedes is immediately apparent. In a work Vivianni tells us he

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wrote back in fifteen eighty six,
and it survives in several manuscript copies,

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titled The Little balance. Archimedes is
and was famous for crying eureka as he

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leapt from the bath and ran naked
through the streets of Syracuse. It's solved

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a problem that seemed insolvable. Hero
the King of Syracuse, had given a

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goldsmith some gold from which a crown
had been made. The crown weighed the

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same as the gold out of which
which it was supposed to have been made,

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but the king came to suspect that
the goldsmith had adulterated the gold with

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silver and had stolen some. He
was, however, reluctant to melt the

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crown down in order to find out
whether or not his suspicion was justified.

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One day, Archimedes noticed that as
he got out of the bath, the

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level of the water rose. By
putting the crown in a tank, one

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could measure the amount of water it
displaced. Silver weighs less than gold,

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so a crown of silver would be
larger than a crown made of the same

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weight of gold. By measuring the
volume of the crown, one could tell

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approximately the portion of silver and gold
in it. This has always been seen

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as an example of Archimedes' brilliance as
a scientist. Not in Galleo's view though,

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because the proposed solution was too crude, the measurements would be merely rough.

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It wasn't worthy of Archimedes. What
he must have done is take a

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00:31:00.440 --> 00:31:03.400
very precise balance and use it to
weigh the crown in both air and in

325
00:31:03.480 --> 00:31:08.480
water. For it's much easier to
measure weights exactly than it is to measure

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00:31:08.599 --> 00:31:14.640
volumes exactly. By doing the same
with both gold and silver, you could

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00:31:14.680 --> 00:31:21.559
work out exactly how much heavier than
water gold silver the crowns were. What

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Galileo was introducing was a concept called
specific gravity, and he goes on to

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provide a table of specific gravities of
different materials. Once you knew the specific

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gravity of gold, silver, and
the crown, you could tell exactly,

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not just approximately, what the crown
was made of. The concept of specific

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gravity is important, and Galileo was
putting it too sophisticated use. But Archimedes

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00:31:48.720 --> 00:31:53.799
had the concept too, and here's
the key. The difference between Galileo and

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Archimedes is that Galileo wanted to measure
more exactly, and having measure one substance,

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00:32:00.480 --> 00:32:06.000
he wanted to go on and measure
others, and thus in order to

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00:32:06.079 --> 00:32:09.880
do this, he had to devise
a new method of measurement. Hence,

337
00:32:10.160 --> 00:32:15.160
one of the key things that changes
during Galileo's life in terms of science is

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00:32:15.200 --> 00:32:21.640
the desire to be not just close, but exact. If nothing else.

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00:32:22.119 --> 00:32:30.640
The little balance shows that from the
very beginning Galileo was preoccupied with precise measurements.

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Yet this would be crucial to his
development as an astronomer and eventually a

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00:32:37.400 --> 00:32:44.440
scientist. Shortly after writing his work
on pendulums, in the last months of

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00:32:44.480 --> 00:32:50.960
fifteen eighty seven, Galleos sent to
the leading mathematicians of northern Italy his solutions

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00:32:51.240 --> 00:32:54.960
to a problem that derived from Archimedes'
work. He had been working on this

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00:32:55.079 --> 00:33:00.720
problem for a couple of years.
It was presented to him by his first

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00:33:00.720 --> 00:33:07.359
patron, whose work was to have
a significant influence on Galileo up until the

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00:33:07.400 --> 00:33:13.279
time of his death. The issue
was how do you calculate the center of

347
00:33:13.480 --> 00:33:20.839
gravity of various solids, and Galileo
remained sufficiently fond of his solutions to publish

348
00:33:20.880 --> 00:33:25.799
them at the end of his life. The first problem addressed by Galileo was

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00:33:25.799 --> 00:33:30.640
that of determining the center of the
gravity of a yard arm, which has

350
00:33:30.680 --> 00:33:37.200
spread along its equal distances a series
of five weights, each weight weighing from

351
00:33:37.559 --> 00:33:44.799
one to five units. His solution
to the problem puzzled leading professors of mathematics

352
00:33:45.079 --> 00:33:50.839
at the Jesuit College in Rome.
Surely he had defined the problem in such

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00:33:50.880 --> 00:33:55.880
a way that the solution was already
included in the definitions. Galleo's response to

354
00:33:55.920 --> 00:34:00.640
these inquiries was not to restate his
proof indifferent terms. It was not to

355
00:34:01.079 --> 00:34:06.200
argue that the proof was valid and
did not include the logical flaw that they

356
00:34:06.200 --> 00:34:10.679
were attributing to it. It was
to send both of his correspondents a new

357
00:34:10.800 --> 00:34:15.960
drawing of the problem, in which
the five weights were bunched up together instead

358
00:34:16.000 --> 00:34:20.920
of being spread out. If they
looked at the drawing, he said,

359
00:34:21.599 --> 00:34:29.719
they would understand his solution. One
man found Galileo's response satisfactory, but another

360
00:34:29.760 --> 00:34:35.320
repeated that this was not a proof. Strictly speaking, Galileo's reply was no

361
00:34:35.480 --> 00:34:39.599
reply at all. His response to
a question about logic was to offer a

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00:34:39.639 --> 00:34:45.559
different way of visualizing the problem.
His claim was that you could see that

363
00:34:45.639 --> 00:34:52.119
his answer was correct. Galileo's argument
may not be logical, but we are

364
00:34:52.559 --> 00:34:58.360
likely today to find it convincing because
we live in a culture. We're seeing

365
00:34:58.840 --> 00:35:04.679
is believing. We have X rays, we have CT scans, we have

366
00:35:05.039 --> 00:35:10.599
a brand new telescope that can gaze
billions of miles into the distance. Ours

367
00:35:10.679 --> 00:35:16.039
is of visual culture, and Galileo
is one of the people who constructed that

368
00:35:16.159 --> 00:35:23.000
culture. One of the great puzzles
of history is why it took three hundred

369
00:35:23.079 --> 00:35:30.800
years to invent the telescope. Eyeglasses
were invented in twelve eighty four. The

370
00:35:30.880 --> 00:35:37.880
telescope, which was basically just a
combination of two lenses from glasses, did

371
00:35:38.000 --> 00:35:45.960
not come around until sixteen oh eight. One answer is that the telescope and

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00:35:45.000 --> 00:35:51.760
the microscope are profoundly problematic because they
require you to rely on one sense,

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and one sense alone, the sense
of sight. Sight had always been regarded

374
00:35:58.440 --> 00:36:02.440
as the sense which was most easily
deceived. What is perspective painting, of

375
00:36:02.480 --> 00:36:08.760
course, but a deception of the
eye. The apostle Thomas didn't believe that

376
00:36:08.880 --> 00:36:15.079
Jesus had risen from the dead when
he saw him. Belief came only after

377
00:36:15.119 --> 00:36:20.360
he touched him. And after all, what most lenses do is they magnify

378
00:36:20.960 --> 00:36:27.679
and they distort it. They are
deceptive. The fundamental realization that our own

379
00:36:27.760 --> 00:36:31.840
capacity to see depends on a lens
within the eye came only with Kepler's production

380
00:36:31.920 --> 00:36:38.400
of optics in sixteen oh four,
just before the invention of the telescope,

381
00:36:38.480 --> 00:36:43.280
and so sight, particularly when dependent
on a lens, was to be trusted

382
00:36:43.840 --> 00:36:47.039
only when it could be confirmed by
touch, sound, or smell. To

383
00:36:47.079 --> 00:36:52.000
take the idea of a telescope seriously, you must entrust yourself to your eyes,

384
00:36:53.199 --> 00:36:58.800
turning into the heavens. You had
to trust it to provide information on

385
00:36:58.840 --> 00:37:02.880
a world you would never be able
to touch, or gear or smell.

386
00:37:05.199 --> 00:37:09.559
Galileo was willing to do that.
He was willing to entrust himself to his

387
00:37:09.719 --> 00:37:15.880
eyes, hence his conviction that the
telescope could tell him all he needed to

388
00:37:16.000 --> 00:37:22.079
know. But the scale of the
cultural resistance to purely visual information is easy

389
00:37:22.119 --> 00:37:30.079
to illustrate because astronomers had always relied
on such information. According to the astronomers,

390
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the planets moved along complicated paths through
the skies at the cycles on circles,

391
00:37:37.960 --> 00:37:45.079
effectively spirals. According to the philosophers, these were merely hypotheses to quote

392
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save the appearances end quote workarounds to
produce results that matched the data In reality.

393
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They insisted the planets were attached to
crystalline orbs that performed perfect circles in

394
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the heavens. The result was mutually
incomprehensible. This was clearly the case when

395
00:38:06.719 --> 00:38:13.079
in sixteen sixteen, a Catholic cardinal
argued Copernicanism was a hypothesis, just like

396
00:38:13.159 --> 00:38:17.000
epicycles. No one thought they were
real, so what's the point in worrying

397
00:38:17.000 --> 00:38:23.800
about whether or not Copernicism was true. Galleo's response was simple. Every astronomer

398
00:38:23.840 --> 00:38:30.239
thought epicycles were real, and every
Copernican thought that Copernicism was true. But

399
00:38:30.280 --> 00:38:36.480
the astronomers could not see their epicycles. They deduced their existence from compiling tables

400
00:38:36.840 --> 00:38:40.519
in which they recorded locations of planets
in the sky. What they could see

401
00:38:40.800 --> 00:38:45.800
and what they could believe were two
different things, even if the astronomer's knowledge

402
00:38:45.840 --> 00:38:53.000
was grounded in visual information. The
astronomers by sixteen sixteen not only had new

403
00:38:53.039 --> 00:38:58.920
evidence of the telescope, they were
working in a culture which was increasingly receptive

404
00:38:58.960 --> 00:39:05.599
to visual information. It's a nice
coincidence that the first recorded instance of the

405
00:39:05.599 --> 00:39:12.880
phrase seeing in believing in English dates
to sixteen oh nine, the year of

406
00:39:13.000 --> 00:39:21.480
Galileo's first telescopic observation. Galileo was
well aware that the revolution he was seeking

407
00:39:21.480 --> 00:39:25.760
to bring about required a new attitude
to the senses and to vision. In

408
00:39:25.800 --> 00:39:32.800
particular, We who take that attitude
for granted have great difficulty in imagining the

409
00:39:32.840 --> 00:39:38.800
obstacles Galileo and his friends first had
to overcome. In the dialogue, he

410
00:39:39.239 --> 00:39:44.960
or rather the person speaking for him, tells the following story. This is

411
00:39:45.000 --> 00:39:49.920
a lengthy quotation. One day I
was at the home of a very famous

412
00:39:49.920 --> 00:39:53.840
doctor in Venice, where many pearsons
came on account of their studies, and

413
00:39:53.920 --> 00:40:00.159
others occasionally came out of curiosity to
see some anatomical dissection performed by a man

414
00:40:00.360 --> 00:40:05.800
who was truly no less learned than
he was, a careful and expert anatomist.

415
00:40:06.760 --> 00:40:09.119
It happened on this day that,
when he was investigating the source and

416
00:40:09.159 --> 00:40:15.039
origin of the nerves, about which
there exists a notorious controversy between the gallonist

417
00:40:15.239 --> 00:40:21.599
and parapactic doctors, the anatomist showed
that the great trunk of nerves, leaving

418
00:40:21.599 --> 00:40:24.960
the brain and passing through the nape
of the neck, extended on down the

419
00:40:25.000 --> 00:40:30.679
spine, and then branched out through
the whole body and that only a single

420
00:40:30.760 --> 00:40:35.440
strand as fine as a thread rived
at the heart. Turning to a gentleman

421
00:40:35.880 --> 00:40:39.760
whom he knew to be a parapactic
philosopher, and on whose account he was

422
00:40:39.800 --> 00:40:45.360
exhibiting and demonstrating everything with unusual care, he asked this man whether he was

423
00:40:45.400 --> 00:40:52.320
at last satisfied and convinced that the
nerves originated in the brain and not in

424
00:40:52.360 --> 00:40:58.880
the heart. The philosopher, after
considering for a while, answered, you

425
00:40:58.920 --> 00:41:05.039
have made me seen this so plainly
that if Aristotle's text were not contrary to

426
00:41:05.119 --> 00:41:09.239
it, stating clearly that the nerves
originate in the heart, I should be

427
00:41:09.320 --> 00:41:17.519
forced to admit it was true.
End quote. Thus, for Aristotelians,

428
00:41:19.159 --> 00:41:27.639
seeing was never the same as believing, But for Galileo, seeing was believing,

429
00:41:28.400 --> 00:41:34.719
and this is one of the biggest
changes Galileo brings to Western science.

430
00:41:36.199 --> 00:41:43.000
Galileo put a lot of emphasis on
diagrams and visual representations of the truth.

431
00:41:43.960 --> 00:41:50.000
Galleo believed that a mathematician without a
diagram was only half a mathematician at best.

432
00:41:51.119 --> 00:41:57.320
There are various ways to interpret Galileo's
method of thinking with diagrams. It

433
00:41:57.440 --> 00:42:00.639
was, of course, to an
extent, a personal peculiarity. Galileo might

434
00:42:00.639 --> 00:42:05.840
have been an artist, the diagrams
that he did are that good. But

435
00:42:05.920 --> 00:42:12.360
Galileo's insistence on diagrams was also just
part of a bigger cultural shift. The

436
00:42:12.400 --> 00:42:19.039
printing press and advances therein had made
the reproduction of high quality images for the

437
00:42:19.079 --> 00:42:25.679
first time possible, so to an
extent, Galileo also sensed a change and

438
00:42:25.760 --> 00:42:32.599
decided to ride the wave. As
I mentioned before, we know very little

439
00:42:32.639 --> 00:42:40.119
about Galileo's early life even after sixteen
ten. What we see of Galileo is

440
00:42:40.199 --> 00:42:45.880
mainly what he wanted us to see. Those thoughts and feelings he chose to

441
00:42:45.920 --> 00:42:52.639
conceal have long seemed forever lost.
There is, however, one source which

442
00:42:52.760 --> 00:42:57.320
enables us to kind of get a
glimpse into the real thinkings in life of

443
00:42:57.400 --> 00:43:02.960
a younger Galileo. In early fifteen
eighty nine, Galileo was trying to establish

444
00:43:04.039 --> 00:43:08.800
himself as a mathematician and doing some
tutoring on the side. Seems like he

445
00:43:08.840 --> 00:43:15.079
had taught mathematics in Florence and in
Siena, and in that spring of fifteen

446
00:43:15.119 --> 00:43:20.280
eighty nine he was living in Pisa, having taught in a local monastery.

447
00:43:20.360 --> 00:43:25.079
He returned from Pisa to Florence,
about sixty miles to celebrate Easter, and

448
00:43:25.119 --> 00:43:31.119
fell in with an old friend,
a guy by the name of Giovambattista Ricae

449
00:43:31.199 --> 00:43:37.360
Soli, who was a wealthy young
man. They studied philosophy, mathematics,

450
00:43:37.360 --> 00:43:42.960
and poetry together, as friends did
on the Renaissance. They slept in the

451
00:43:42.960 --> 00:43:49.079
same bed. One night, giom
Vambista woke him. A year later,

452
00:43:49.440 --> 00:43:53.599
Galileo could still remember giovan Bista reaching
for him, getting his arm around his

453
00:43:53.760 --> 00:43:59.960
neck, and assured him that he
Giombandista, had been condemned to death.

454
00:44:00.320 --> 00:44:05.679
What would happen to him? Did
Galileo think? Would he be executed by

455
00:44:05.679 --> 00:44:10.119
having his head chopped off, or
would he be burnt alive? His crime

456
00:44:10.320 --> 00:44:15.719
was to have been given a funeral
address for the Grand Duke when the Grand

457
00:44:15.840 --> 00:44:21.559
Duke was still alive. He had, in fact given such an address to

458
00:44:21.599 --> 00:44:27.840
the local Academy, an organization of
young intellectuals, and it was half serious,

459
00:44:28.239 --> 00:44:32.199
half playful. But the crime was
actually that the Grand Duke was dead,

460
00:44:32.880 --> 00:44:38.480
having died on the October seventeenth,
fifteen eighty seven. Night after night,

461
00:44:38.559 --> 00:44:44.280
for thirty days and nights, Galleo
struggled to persuade his friend that no

462
00:44:44.320 --> 00:44:50.400
one had condemned him to death,
but without success. Geo Vambista was mad,

463
00:44:50.480 --> 00:44:53.719
he was insane and was going about
in public wearing mourning clothes for his

464
00:44:53.760 --> 00:45:00.559
own funeral. Eventually, hoping to
escape justice, he ran away to Stoia

465
00:45:00.039 --> 00:45:05.159
and was brought back a prisoner by
his relatives. It was clear, though,

466
00:45:05.159 --> 00:45:07.400
that he was going to set out
again, and it was agreed by

467
00:45:07.440 --> 00:45:13.960
his family that Galileo and a relative
would travel with him to ensure his safety.

468
00:45:14.960 --> 00:45:19.320
So Gio Bambisti, together with one
of his relatives, and Galileo,

469
00:45:19.920 --> 00:45:24.440
set off across northern Italy, wandering
from place to place, traveling sometimes by

470
00:45:24.519 --> 00:45:31.559
night, sometimes off the beaten path, as Giobombista fled his imaginary enemies.

471
00:45:32.840 --> 00:45:37.119
A couple of days before whit Sunday, which is seven weeks after Easter,

472
00:45:38.000 --> 00:45:45.480
they arrived in Genoa, where they
finally were able to persuade their insane friend

473
00:45:45.800 --> 00:45:52.239
to seek medical advice. Twelve days
later, Galileo returned to Florence to take

474
00:45:52.320 --> 00:45:59.440
care of business. Some eight weeks
had now passed since Giovambista had woken Galileo

475
00:45:59.519 --> 00:46:06.119
in the middle of the night to
discuss his coming execution. They next met

476
00:46:06.159 --> 00:46:09.400
near the end of September, when
Galileo set out with some relatives to try

477
00:46:09.440 --> 00:46:15.719
to persuade Giovambista. When the meantime
had traveled to Milan and Rome to return

478
00:46:15.760 --> 00:46:22.039
to Florence, he found his friend
still wearing the clothes in which he had

479
00:46:22.039 --> 00:46:25.119
set out on his travels in the
spring and unable to sleep through the night.

480
00:46:27.559 --> 00:46:31.880
By this time, Giobambista had donated
all his worldly goods to his relatives.

481
00:46:34.159 --> 00:46:38.119
Throughout the weeks that Galileo was in
gio Bambista's company, his friend was

482
00:46:38.400 --> 00:46:43.880
spending as though he thought he only
had days to live. None of this

483
00:46:44.000 --> 00:46:49.800
money ended up in Galileo's hands.
When Giobambista lost money to Galileo playing cards,

484
00:46:50.320 --> 00:46:53.400
Galleo tried to return the money to
him, he paid towards his own

485
00:46:53.480 --> 00:47:01.079
board and lodging in Genua. Now. Later on, Giovambisti's relatives accused Galileo

486
00:47:01.159 --> 00:47:06.719
of stealing money from him in genuine
but no one seems to believe the relatives,

487
00:47:06.760 --> 00:47:10.840
and it's easy to imagine why.
On one occasion, Giovambisti had caused

488
00:47:10.840 --> 00:47:15.960
someone to mistake Galleo for a bandit
and take aim at him with an arquebus,

489
00:47:15.719 --> 00:47:22.440
but fortunately the powder was damp.
Galileo had been greatly distressed by this

490
00:47:22.519 --> 00:47:28.199
incident, but still he did not
abandon his friend. In fact, it's

491
00:47:28.239 --> 00:47:34.400
evident that Galileo was genuinely fond of
his companion. In trial documents, he

492
00:47:34.480 --> 00:47:38.840
always speaks him with respect and insists
there is no disgrace in lunacy, for

493
00:47:38.960 --> 00:47:45.880
disgrace comes only from those things over
which we have control. He was in

494
00:47:45.920 --> 00:47:51.800
a difficult position throughout, acting both
as Gioe Bambisti's friend and as an agent

495
00:47:51.840 --> 00:47:55.639
of his family, who were trying
to prevent him from coming to harm.

496
00:47:57.239 --> 00:48:00.519
We may guess he was strongly opposed
to those who wanted to solve the problem

497
00:48:00.840 --> 00:48:06.840
by tying up Giovambisti and holding him
prisoner, But he seems to have kept

498
00:48:06.840 --> 00:48:13.039
the respect of everyone concerned. It
is true that this little adventure wasn't without

499
00:48:13.039 --> 00:48:19.159
its benefits. It gave Galileo an
opportunity to see what he referred to as

500
00:48:19.480 --> 00:48:27.039
the world, but only a patient
and benevolent person could have stood Giovambisti's company

501
00:48:27.360 --> 00:48:32.920
month after month. It's worth stressing
this because Galileo was not a particularly good

502
00:48:32.960 --> 00:48:38.039
father and Frankly, later in life, he rarely showed any interest in the

503
00:48:38.039 --> 00:48:44.280
welfare of others. His work was
soon to become more important to him than

504
00:48:44.320 --> 00:48:49.000
his loved ones. If we are
going to look at his character, though,

505
00:48:49.519 --> 00:48:52.599
and if you're going to make an
argument that Galileo had a good character,

506
00:48:52.679 --> 00:48:57.519
a strong character, it must be
given on the strength of these months

507
00:48:57.559 --> 00:49:04.360
in fifteen eighty nine that he spent
day and night in gioe Bambisti's company trying

508
00:49:04.400 --> 00:49:08.199
to ensure that his friend came to
no harm. But if we're going to

509
00:49:08.239 --> 00:49:15.159
continue to look at Galileo's character,
that brings us to one of the trickiest

510
00:49:15.320 --> 00:49:22.400
issues when it comes to modern day
Galileo scholarship. Several scholars have devoted whole

511
00:49:22.480 --> 00:49:30.480
volumes to this said issue. In
this case is Aristotle. Aristotle was the

512
00:49:30.119 --> 00:49:38.559
authority in modern Europe for centuries.
Aristotelian logic was the only acceptable method for

513
00:49:38.679 --> 00:49:45.000
debate and logical reasoning in Western Europe, and such absolutely was the case in

514
00:49:45.039 --> 00:49:53.480
the early seventeenth century. Galileo eventually
becomes known as the most aggressive anti Aristotelian

515
00:49:53.559 --> 00:50:00.320
of his age. It's therefore difficult
to discover that he described himself in sixteen

516
00:50:00.480 --> 00:50:07.119
forty, at the very end of
his life as a good Aristotelian. What

517
00:50:07.199 --> 00:50:12.840
in the world are we to make
of this? Amongst Galileo's surviving papers,

518
00:50:12.880 --> 00:50:20.039
there are three philosophical texts, two
treatises on Aristotle's posterior Analytics and one on

519
00:50:20.079 --> 00:50:25.280
Aristotles on the Heavens. At first
blush, these all look like pro Aristotle

520
00:50:25.360 --> 00:50:31.800
works, but the problem for relying
on these is that they're not scholarly works.

521
00:50:32.760 --> 00:50:39.760
What we have here are Galileo's notes
on other people's lectures. In essence,

522
00:50:40.320 --> 00:50:47.679
these treatises parrot other people's ideas,
not Galileos. Hence we need to

523
00:50:47.719 --> 00:50:53.840
discout in them as evidence that Galileo
was an Aristotelian. And neither is the

524
00:50:53.880 --> 00:50:59.719
comment that Galileo made in sixteen forty
dispositive as to whether or not he was

525
00:50:59.760 --> 00:51:06.039
a quote unquote good Aristotelian. We
have to remember this was well after the

526
00:51:06.039 --> 00:51:13.199
Inquisition trial. His comment was probably
much more about saving face and ensuring that

527
00:51:13.280 --> 00:51:16.599
he was no longer a target for
Rome than about anything he really believed.

528
00:51:19.000 --> 00:51:22.039
I really hope that by the end
of this series you accept the argument that

529
00:51:22.119 --> 00:51:29.320
Galileo truly was something new. He
was not an Aristotelian by any stretch of

530
00:51:29.360 --> 00:51:35.960
the imagination. He was a new
breed of scientists. In fact, he

531
00:51:36.039 --> 00:51:52.079
might have been the first ever modern
scientist. In the autumn of fifteen eighty

532
00:51:52.159 --> 00:51:58.159
nine, Galleo became a professor of
mathematics at the University of Pisa. He

533
00:51:58.199 --> 00:52:01.840
had taken the first step on a
to a professional career and to financial security.

534
00:52:02.880 --> 00:52:08.199
But frankly, we should not harbor
any illusions about this first posting.

535
00:52:08.679 --> 00:52:15.920
It was one hundred percent a first
job, right. The salary was significantly

536
00:52:15.440 --> 00:52:20.599
lower than might be expected. In
fact, he was paid sixty florins,

537
00:52:20.679 --> 00:52:23.960
and to sort of put that into
context, that was a lot less than

538
00:52:24.000 --> 00:52:30.000
a yearly income for a decent Stonemason. It was not possible to become a

539
00:52:30.079 --> 00:52:37.039
gentleman on such an income. There
were professors of philosophy in prestigious universities and

540
00:52:37.320 --> 00:52:44.039
institutions who were earning fifteen times as
much as Galileo. In fact, one

541
00:52:44.079 --> 00:52:50.239
of Galileo's closest friends was earning seven
hundred florins a year at Pisa. And

542
00:52:50.280 --> 00:52:53.559
this wasn't just because Galileo was starting
out. The fact of the matter is

543
00:52:54.159 --> 00:53:01.079
mathematics was not a prestigious subject as
far as other professors were concerned. It

544
00:53:01.159 --> 00:53:08.480
had two really sort of plebeian functions. One introduce philosophy students to basic geometry

545
00:53:08.840 --> 00:53:14.480
and thus the ideas of a proof, and to provide medical students with the

546
00:53:14.519 --> 00:53:21.920
skills required to look at different astrological
charts. Mathematics was regarded as intellectually uninteresting.

547
00:53:22.519 --> 00:53:28.159
It was purely technical, and the
salary of mathematicians reflected this. Now,

548
00:53:28.159 --> 00:53:32.000
Galileo had been a student at Pisa
as late as fifteen eighty five,

549
00:53:32.079 --> 00:53:37.360
and so when he got there he
would have had old friends. So it's

550
00:53:37.440 --> 00:53:42.079
highly likely that he found himself picking
up on intellectual discussions that had interested him

551
00:53:42.119 --> 00:53:47.559
as a student. The intellectual life
in Pisa was dominated by two different philosophers,

552
00:53:47.639 --> 00:53:55.480
Girolamo Boro and Francisco Buonacamicki. In
fifteen seventy five, Boro had published

553
00:53:55.480 --> 00:54:00.480
a book on the movement of heavenly
and light bodies. Galileo actually owned a

554
00:54:00.480 --> 00:54:05.760
copy. In fifteen eighty nine,
bon Amiki had on his desk an enormous

555
00:54:05.800 --> 00:54:09.119
manuscript on the same subject, although
the book didn't appear into print until fifteen

556
00:54:09.199 --> 00:54:15.480
ninety one. Galleo had probably attended
boon Amiki's lectures as a student, so

557
00:54:15.519 --> 00:54:19.840
the main arguments in the book would
have been familiar to him even before he

558
00:54:19.880 --> 00:54:25.079
read it. Now, Boro and
Bonamiki disagreed radically on movement, as with

559
00:54:25.159 --> 00:54:30.639
most other things, and their colleagues
and students were certainly aware of their disputes,

560
00:54:31.440 --> 00:54:37.800
particularly as students were required to engage
in disputations, debates in which they

561
00:54:37.840 --> 00:54:42.239
take one side or the other.
This was sort of a standard lesson planned

562
00:54:42.320 --> 00:54:47.639
in medieval academic circles. Disagreements thus
lay at the very core of intellectual life,

563
00:54:49.000 --> 00:54:52.960
and students were taught to approach central
issues from sharply contrasting points of view.

564
00:54:53.639 --> 00:54:59.199
At the same time, permissible range
of disagreement was set by the tradition

565
00:54:59.239 --> 00:55:04.920
of commentary, in other words,
by Aristotle. Now, in order to

566
00:55:05.000 --> 00:55:08.280
understand the real dispute between Boro and
Bonamiki, we first need a sense of

567
00:55:08.280 --> 00:55:15.920
those assumptions that all Aristotelians held in
common, assumptions that Galileo was soon to

568
00:55:15.039 --> 00:55:21.639
question, at least in part.
First, Aristotelians drew a sharp distinction between

569
00:55:21.760 --> 00:55:25.519
natural and forced movement. If a
ball is thrown, then that's forced movement.

570
00:55:27.199 --> 00:55:30.280
If it's dropped, it moves to
its natural place of rest, and

571
00:55:30.320 --> 00:55:35.639
that's natural movement. If it's thrown
upwards, then the ball decelerates as it

572
00:55:35.760 --> 00:55:39.679
rises, and this is because force
movements tend to just peter out. If

573
00:55:39.719 --> 00:55:44.440
it's dropped, it it accelerates,
and this is because natural movements tend to

574
00:55:44.440 --> 00:55:47.400
speed up. If a ball is
thrown, then there's initial forced movement,

575
00:55:47.480 --> 00:55:52.840
and then the ball drops downward.
Aristotelians believe that only one type of movement

576
00:55:52.920 --> 00:55:59.119
could take place at a time.
Thus a ball traveled in a straight line

577
00:55:59.119 --> 00:56:02.599
and then draw vertically if you threw
it. They also held the view that

578
00:56:02.599 --> 00:56:08.199
any objects subjected to a force movement
must be being moved by another object,

579
00:56:08.480 --> 00:56:12.199
or, in the case of the
hand, by the will of the sentient

580
00:56:12.239 --> 00:56:16.079
creature. It appeared to follow from
this argument that once the ball leaves the

581
00:56:16.159 --> 00:56:21.519
hand, it ought, in principle, to come to a stop. Aristotle

582
00:56:21.599 --> 00:56:23.800
sought to solve this problem by arguing
that the ball was pushed on its way

583
00:56:23.840 --> 00:56:28.159
by the air, which had been
disturbed by the movement of the hand.

584
00:56:29.199 --> 00:56:34.320
Later theorists argued that the ball had
acquired some sort of internal energy or impressed

585
00:56:34.320 --> 00:56:37.920
force, just as it might acquire
heat from the hand and stay hot even

586
00:56:37.960 --> 00:56:43.519
after it had been let go.
Galileo would have found an account of impressed

587
00:56:43.559 --> 00:56:49.400
force in a textbook by Jesuit philosopher
Benedict Pereira, which he used while working

588
00:56:49.400 --> 00:56:55.559
on his first study of falling bodies
on motion. Crucially, all Aristotelians held

589
00:56:55.559 --> 00:57:01.480
the view that the heavier a ball
was, the faster it would fall.

590
00:57:04.079 --> 00:57:07.960
Now, all of this, of
course, seems really bizarre to us.

591
00:57:07.400 --> 00:57:13.559
Definitely does to me, especially when
you consider the movement of an obvious projectile.

592
00:57:14.760 --> 00:57:19.119
Aristotelians believed, however, that the
universe consisted not only of weight but

593
00:57:19.159 --> 00:57:25.719
of lightness. If balls naturally move
downwards, flames naturally move upward. Boro

594
00:57:25.920 --> 00:57:32.239
and Bonamiki were thus debating the natural
movement of bodies downward and upwards, both

595
00:57:32.320 --> 00:57:38.000
movements they held continued until the body
was obstructed or reached its natural place of

596
00:57:38.039 --> 00:57:42.400
rest. In the case of a
heavy body, this would actually be at

597
00:57:42.400 --> 00:57:45.519
the center of the Earth. In
the case of a light body, it'd

598
00:57:45.519 --> 00:57:51.960
be an invisible frontier between the Earth
and the Moon. I guess somewhere in

599
00:57:52.000 --> 00:57:58.119
the stratosphere. Because beyond this frontier, the only natural movement was circular movement.

600
00:57:58.719 --> 00:58:02.280
All the heavenly bodies moved in perfect
circles, So once you got up

601
00:58:02.280 --> 00:58:07.360
there, the rules of the game
changed again, at least according to the

602
00:58:07.400 --> 00:58:13.639
followers of Aristotle in the heavens,
what looked like change if you looked long

603
00:58:13.800 --> 00:58:20.880
enough, was just repetition. So
if the heavier body is the faster it

604
00:58:21.000 --> 00:58:25.840
falls. But what is meant by
heavy here? And what did Aristotle mean

605
00:58:27.280 --> 00:58:34.639
by fast? Aristotle was cleared that
speed was proportional to weight, as a

606
00:58:34.639 --> 00:58:37.639
sort of gross example, the body
that weighed twice as much would fall twice

607
00:58:37.679 --> 00:58:43.880
as fast. The much more difficult
question was how do we understand weight.

608
00:58:44.920 --> 00:58:46.960
The standard view was that weight was
to be understood in a normal sense.

609
00:58:47.679 --> 00:58:52.199
A two pound lead weight would fall
twice as fast as a one pound lead

610
00:58:52.239 --> 00:58:58.119
weight. An alternative view was defended
by Bonomiki. Heaviness should be understood as

611
00:58:58.239 --> 00:59:02.559
density or specific gravity, so that
lead weights of different sizes would fall at

612
00:59:02.599 --> 00:59:08.239
the same speed, but they would
all fall faster than wooden balls. Now

613
00:59:08.280 --> 00:59:13.440
confusingly, of course, Boro held
a different view. He thought that weight

614
00:59:13.559 --> 00:59:20.920
was situationally specific and related to the
composition of the material. Aristotelians held that

615
00:59:21.239 --> 00:59:25.760
all earthly objects are made from four
elements earth, water, which are heavy,

616
00:59:27.480 --> 00:59:30.599
fire which is light, and air, which could be either heavy or

617
00:59:30.679 --> 00:59:36.519
light depending on its location. And
they all agreed that a wooden ball contained

618
00:59:36.800 --> 00:59:42.519
more air than did a lead weight. Boro's view was that when you weighted

619
00:59:42.559 --> 00:59:45.599
a wooden ball, the air in
it had no weight, but the moment

620
00:59:45.639 --> 00:59:51.960
it was dropped in air, the
air becomes heavy. Thus, if you

621
00:59:52.000 --> 00:59:54.800
look at a lead weight and a
wooden ball, which weighted the same when

622
00:59:54.800 --> 01:00:00.519
suspended in a balance, the wooden
ball was in fact heavier because when it's

623
01:00:00.559 --> 01:00:07.719
falling, the air inside of it
somehow gets added to the weight. And

624
01:00:07.760 --> 01:00:09.719
again I'm not saying that any of
this is accurate, because it's not.

625
01:00:10.559 --> 01:00:17.159
But these are some of the efforts
that early modern scientists I'm using that word

626
01:00:17.159 --> 01:00:23.760
in air quotes go to try to
make what they see fit Aristotle. And

627
01:00:23.800 --> 01:00:31.880
that's the problem is that coming out
of the medieval age, people at universities

628
01:00:31.920 --> 01:00:39.559
and philosophers are trying desperately to get
that square peg to fit into that round

629
01:00:39.599 --> 01:00:45.519
hole, rather than recognizing that,
oh no, this needs a square peg

630
01:00:45.599 --> 01:00:51.559
hole. Aristotle was wrong. That's
what we can't do. And getting back

631
01:00:51.559 --> 01:00:54.360
to the story for a moment.
Borow had actually put this air heavy theory

632
01:00:54.400 --> 01:01:00.599
to the test. He had gathered
a group of philosophers at his house tossed

633
01:01:00.679 --> 01:01:06.039
comparable wed weights and chunks of wood
out of an upstairs window. The wood

634
01:01:06.159 --> 01:01:10.480
had consistently reached the ground ahead of
the lead. Now Bonomiki wasn't persuaded.

635
01:01:12.320 --> 01:01:15.599
You would first need to weigh the
objects, he said, and make sure

636
01:01:15.599 --> 01:01:22.000
that the weight was identical. And
there was also an obvious problem. The

637
01:01:22.119 --> 01:01:23.800
shorter the drop, the harder it
was to see what was going on.

638
01:01:24.800 --> 01:01:29.360
The only way that you could measure
this was to drop things from a greater

639
01:01:29.599 --> 01:01:37.199
height. And we know that in
sixteen twelve Giorgio Corricio had tried dropping different

640
01:01:37.239 --> 01:01:42.280
objects of different weights but the same
material from the top of the Leaning tower

641
01:01:42.280 --> 01:01:49.199
of Pisa. The result, he
claimed, at least, vindicated Aristotle that

642
01:01:49.280 --> 01:01:53.760
the speed of the fall proved proportional
to the weight. Now, according to

643
01:01:53.800 --> 01:01:59.280
Viviani, Galileo, when he was
teaching at Pisa, so sometime between fifteen

644
01:01:59.280 --> 01:02:06.000
eighty nine and fifteen had already carried
out a test of dropping different objects of

645
01:02:06.079 --> 01:02:09.840
different weights but the same material from
the top of the leaning tower. Pisa,

646
01:02:12.039 --> 01:02:19.679
and he had shown that these reached
the bottom simultaneously. Now, but

647
01:02:19.719 --> 01:02:23.519
this is like Viviani's story of the
pendulum. He wants to present Galileo as

648
01:02:23.519 --> 01:02:30.559
an experimental scientist and to claim that
he was so precocious that he founded modern

649
01:02:30.599 --> 01:02:36.880
physics almost effortlessly. But in this
case, there is a manuscript on natural

650
01:02:36.920 --> 01:02:42.159
motion which was written sometime between fifteen
eighty nine and fifteen ninety two, in

651
01:02:42.199 --> 01:02:46.679
which Galileo confidently claims that he knows
what will happen in such a test.

652
01:02:46.719 --> 01:02:52.159
First, he writes, the lighter
object moves faster, but then it's overtaken

653
01:02:52.199 --> 01:02:55.599
by the heavier object, which reaches
the bottom ahead of it. He has,

654
01:02:55.800 --> 01:03:01.400
he tells, us, done this
experiment many many times times. Thus,

655
01:03:01.440 --> 01:03:06.719
it would seem perfectly straightforward to say
that Galilea was carrying out experiments with

656
01:03:06.840 --> 01:03:12.400
falling bodies while he was at Pisa, and so clearly he was already an

657
01:03:12.440 --> 01:03:20.760
experimental scientist. Historians, however,
have made the simple complicated. In nineteen

658
01:03:20.840 --> 01:03:25.639
thirty five, historian Lane Cooper published
a whole book arguing that Viviani's story was

659
01:03:25.880 --> 01:03:31.519
a myth, just like his story
about the pendulum. In fifteen thirty seven.

660
01:03:32.280 --> 01:03:38.360
The great historian Alexandra Corre, an
enormously influential historian of science, also

661
01:03:38.480 --> 01:03:45.159
dismisses the story as pure myth.
This wasn't a real experiment, he writes,

662
01:03:45.599 --> 01:03:50.159
but an imaginary thought experiment. Now, such skepticism, I think is

663
01:03:50.199 --> 01:03:53.800
well grounded, because, of course, if you drop two objects of the

664
01:03:53.840 --> 01:03:59.199
same material but different weights from a
high tower, you just don't get the

665
01:03:59.320 --> 01:04:04.599
results that Viviani and Galileo describe.
The heavier object is going to hit the

666
01:04:04.639 --> 01:04:09.960
ground well before the lighter object,
and this is because the resistance of the

667
01:04:10.000 --> 01:04:15.559
air has more effect on the lighter
object than it does on the heavier one.

668
01:04:15.639 --> 01:04:19.280
Galileo simply couldn't have carried out this
experiment and obtained the results that are

669
01:04:19.280 --> 01:04:24.760
described by Viviani. He couldn't have
done it. It's not possible now.

670
01:04:24.800 --> 01:04:30.320
Unfortunately, Viviani, Cooper, and
Core and modern physicists who write about high

671
01:04:30.360 --> 01:04:36.679
tower experiments share a fundamental misunderstanding,
one that has profound implications for our whole

672
01:04:36.760 --> 01:04:45.519
understanding of what science is. They
think that experiments are straightforward and that repeating

673
01:04:45.559 --> 01:04:53.360
them is unproblematic. Unfortunately, given
the constraints that Galileo would have been working

674
01:04:53.400 --> 01:05:00.960
with in the early seventeenth century.
That is simply not possible. There's no

675
01:05:01.239 --> 01:05:11.239
way to recreate the standard conditions of
a modern laboratory in seventeenth century Pisa.

676
01:05:11.840 --> 01:05:17.119
That just isn't. Now. In
sixteen thirty eight, Galleo publishes a book

677
01:05:17.199 --> 01:05:24.199
Two New Sciences, in which he
does explain the tower experiment. And again,

678
01:05:25.199 --> 01:05:30.920
while some historians have dismissed that as
just a thought experiment, we know

679
01:05:30.079 --> 01:05:36.599
in sixteen forty one that other people
were physically trying to replicate it, suggesting

680
01:05:36.920 --> 01:05:45.519
at least Galileo's contemporaries believe the experiment
was real. These attempt at replications were

681
01:05:45.559 --> 01:05:51.320
repeated throughout the sixteen forties. Now, all of this does support the claim

682
01:05:51.719 --> 01:06:00.320
that Galileo was truly the world's first
experimental scientist. Just as Viviani wrote that

683
01:06:00.360 --> 01:06:06.000
being said, Galileo's experiment was far
from perfect. It wasn't done in a

684
01:06:06.079 --> 01:06:12.960
vacuum where you could have accounted for
air resistance. And moreover, just think

685
01:06:13.000 --> 01:06:16.920
about it for a second. If
you're trying to drop two objects of the

686
01:06:16.960 --> 01:06:24.079
same material, let's say lead,
but of different sizes physically, that's hard

687
01:06:25.039 --> 01:06:29.079
imagine trying to drop a musketball you
could hold that very easily in your fingers,

688
01:06:29.920 --> 01:06:33.760
and a cannon ball at the same
time. The cannon ball requires a

689
01:06:33.880 --> 01:06:40.559
lot more grip strength to hold it
aloft and let go at the exact same

690
01:06:40.639 --> 01:06:44.400
time you're letting go of the musketball. And that's one of the biggest problems

691
01:06:44.440 --> 01:06:48.519
here, is that the two objects
must be released at the identical moment,

692
01:06:48.599 --> 01:06:56.159
or the whole experiment is not valid, and so it's extremely unlikely that one

693
01:06:56.280 --> 01:07:00.239
or even two people could manage to
drop both a musketball and a cannonball at

694
01:07:00.239 --> 01:07:03.840
the exact same time. It's just
not likely. Ultimately, Galileo wound up

695
01:07:03.960 --> 01:07:11.079
arguing that his theoretical model was more
reliable than his real world experiment, arguing

696
01:07:11.119 --> 01:07:15.440
that two objects do fall at the
same rate, even though that was flatly

697
01:07:15.480 --> 01:07:21.400
contradicted by the evidence at hand,
proving once again the staying power of deductive

698
01:07:21.440 --> 01:07:29.639
reasoning and Aristotle. Galleo also recounted
a slope experiment around the same time.

699
01:07:30.480 --> 01:07:33.480
Again, he reasoned that two objects
should roll down the slope at the same

700
01:07:33.559 --> 01:07:40.960
speed, regardless as to their weight. But again Galileo was doing the experiment

701
01:07:41.519 --> 01:07:46.199
in an effort to prove his theory. When the results of the experiment didn't

702
01:07:46.239 --> 01:07:55.639
match the theory, he did not
reconsider the latter, considering the difference between

703
01:07:55.840 --> 01:08:01.159
theory and practicality. From the standpoint
of rates of fall, so gravity,

704
01:08:02.039 --> 01:08:06.280
going back to kind of what Galileo
was trying to prove. According to Aristotle,

705
01:08:06.760 --> 01:08:11.079
rates of fall were determined by the
ratio between the weight of an object

706
01:08:11.599 --> 01:08:16.439
the density of whatever was falling through. Aristotle believed that a vacuum was impossible,

707
01:08:16.840 --> 01:08:19.520
but if there were to be such
a thing, the rate at which

708
01:08:19.520 --> 01:08:24.800
an object fell through a vacuum would
be infinite, corresponding to the weight of

709
01:08:24.840 --> 01:08:29.720
the objects divided by zero. The
object would no sooner enter the vacuum than

710
01:08:29.720 --> 01:08:32.880
it would emerge from the other side. It would be essentially instantaneous. It'd

711
01:08:32.880 --> 01:08:39.239
be at two places at once,
it'd be that fast. Archimedes had proposed

712
01:08:39.239 --> 01:08:44.239
that weight could be established by subtraction, so the object's absolute weight minus the

713
01:08:44.279 --> 01:08:48.760
weight of the medium that it to
places. Others had argued something similarly.

714
01:08:49.720 --> 01:08:54.039
In the case of the rate of
fall in a vacuum, the rate would

715
01:08:54.079 --> 01:09:00.039
be determined by an object's specific gravity. Any led object would fall in a

716
01:09:00.039 --> 01:09:04.199
acum at a constant speed ten times
faster than any wooden object, and since

717
01:09:04.479 --> 01:09:09.159
air weighs very little, the difference
would be nearly the same in air.

718
01:09:10.199 --> 01:09:14.880
A simple thought experiment showed the need
to think in terms of specific gravity rather

719
01:09:14.920 --> 01:09:19.279
than in total weights. According to
Aristotle, a two pound weight would drop

720
01:09:19.319 --> 01:09:24.399
twice as fast as a one pound
weight. But supposing you attach two to

721
01:09:24.439 --> 01:09:28.119
one pound weights together with a metal
rod, Now, at what speed does

722
01:09:28.159 --> 01:09:30.279
it go? From one point of
view, it's now a two pound weight,

723
01:09:30.920 --> 01:09:35.880
but at the same time it's obviously
still two separate one pound weights.

724
01:09:36.640 --> 01:09:41.680
The only logical conclusion is that the
object falls at exactly the same rate as

725
01:09:41.720 --> 01:09:45.720
before. Consequently, all objects of
the same material, no matter how much

726
01:09:45.760 --> 01:09:50.800
they weigh, will fall the same
speed. Now, so this is Galileo's

727
01:09:50.880 --> 01:09:57.680
basic theory. In on Motion,
he rejects the Aristotelian assumption that there are

728
01:09:57.760 --> 01:10:02.239
upward tending objects as well as down
tending ones, but he accepts the Aristotelian

729
01:10:02.279 --> 01:10:09.079
assumption that amongst downward tending objects,
heavy objects will fall faster than lighter ones.

730
01:10:09.880 --> 01:10:15.960
Speed of fall should be constant,
determined by specific gravity. Galleo takes

731
01:10:15.000 --> 01:10:20.000
it as assumed that where one force
is continuously at work, the result and

732
01:10:20.079 --> 01:10:25.840
absence of other factors is always going
to be a constant speed. But if

733
01:10:25.880 --> 01:10:30.239
you actually drop an object, it
starts from being stationary and accelerates downward.

734
01:10:31.359 --> 01:10:36.560
Why is this, Galleo says,
It's because it has an impressed force that

735
01:10:36.640 --> 01:10:43.159
only gradually wears a way, just
as in iron, losing heat more rapidly

736
01:10:43.279 --> 01:10:48.520
than wood. And this explains the
unsatisfactory results obtained in the high tower and

737
01:10:48.640 --> 01:10:56.720
rolling ball experiments. Galleo argued,
these experiments do not measure absolute rates of

738
01:10:56.760 --> 01:11:02.399
fall. They measure only rates of
acceleration. There is no way of measuring

739
01:11:02.439 --> 01:11:08.479
absolute rates of fall. We can
only deduce them from principles. So once

740
01:11:08.520 --> 01:11:13.079
again what we see here is when
Galileo is faced with the reality of the

741
01:11:13.119 --> 01:11:17.560
result of the experiment, he tends
to reject it and lean back on theory.

742
01:11:18.560 --> 01:11:25.720
It was reason, not experience that
generated science, because science is the

743
01:11:25.760 --> 01:11:31.880
study of necessary or causal relationships,
And Galileo says precisely this and on Motion,

744
01:11:33.159 --> 01:11:40.039
and consequently, Galileo could quite happily
declare in On Motion that his high

745
01:11:40.119 --> 01:11:45.960
tower and rolling ball experiments do not
correspond to his theory, but that doesn't

746
01:11:45.039 --> 01:11:51.479
change the reality that the theory is
correct. But there's a further argument in

747
01:11:51.520 --> 01:11:59.720
Galileo's On Motion that any follower of
Aristotle would have found baffling. According to

748
01:11:59.800 --> 01:12:03.960
Aristotle, there are two types of
movement, natural movement, which is directed

749
01:12:03.960 --> 01:12:08.960
towards an end and stops when an
object arrives at its natural resting place,

750
01:12:09.920 --> 01:12:14.960
and forced movement, which continues only
for so long as there is a mover

751
01:12:15.159 --> 01:12:17.640
acting on the moving object. I
talked about this before. This is what

752
01:12:17.680 --> 01:12:23.960
would cause a cannon ball to shoot
straightforward until it runs out of momentum,

753
01:12:24.000 --> 01:12:27.199
and then it would go straight down, which of course it doesn't. In

754
01:12:27.279 --> 01:12:30.640
his book on Motion, as others
had done before him, Galleo modifies the

755
01:12:30.720 --> 01:12:36.600
account of forced movement to include a
new idea impressed force. But he also

756
01:12:36.640 --> 01:12:42.399
invents a quite new type of movement, which he calls intermediate movement. Imagine

757
01:12:42.600 --> 01:12:47.119
a perfectly round ball on a perfectly
smooth sheet of ice. The slightest touch

758
01:12:47.159 --> 01:12:53.159
will start it moving, and it
will continue to move indefinitely. If this

759
01:12:53.199 --> 01:12:58.960
seems like too much abstraction, think
of a river. It flows constantly,

760
01:13:00.119 --> 01:13:05.079
but the gradient is often extremely small. That is the amount that the surface

761
01:13:05.439 --> 01:13:12.000
goes down below it is minute.
It seems that the flowing water has almost

762
01:13:12.039 --> 01:13:16.520
no resistance to movement. Otherwise one
would be able to identify a slope that

763
01:13:16.600 --> 01:13:21.119
was not steep enough for a river
to run down it, but no such

764
01:13:21.800 --> 01:13:30.119
decline exists. Aristotle held that the
natural condition of all non heavenly things is

765
01:13:30.119 --> 01:13:38.239
to be stationary, and that all
movement naturally ends in the cessation of movement.

766
01:13:39.760 --> 01:13:47.159
Galileo is now suggesting that movement might
not have a natural end. This

767
01:13:47.199 --> 01:13:53.840
is a huge break from Aristotle.
Now, the interesting thing about On Motion

768
01:13:54.279 --> 01:14:00.159
is that it's not a finished text. It's a series of drafts and notes

769
01:14:00.680 --> 01:14:06.640
which were evidently abandoned unfinished at some
point. Why did Galileo stop work on

770
01:14:06.720 --> 01:14:14.279
this, especially when there's so many
new groundbreaking principles. Well, unfortunately Galileo

771
01:14:14.439 --> 01:14:18.520
doesn't say so. We're stuck speculating. There are two current theories. The

772
01:14:18.560 --> 01:14:26.119
first is that the experiments described in
On Motion represent the beginning of Galileo's commitment

773
01:14:26.479 --> 01:14:32.479
to a program of experimentation. According
to this theory, On Motion is abandoned

774
01:14:32.960 --> 01:14:41.439
because Galileo could not generate experimental results
that confirmed his theories. Now, this

775
01:14:41.640 --> 01:14:45.520
is kind of hard to believe,
because, as I've talked about many times

776
01:14:45.560 --> 01:14:50.960
in this first episode, there's no
evidence in the early fifteen nineties that Galileo

777
01:14:51.119 --> 01:14:58.760
saw experimental evidence as crucial. When
experimental results were at odds with theory,

778
01:14:58.840 --> 01:15:01.479
he just said it was due to
act accidental factors and stuck with the theory.

779
01:15:03.199 --> 01:15:08.760
Now, the second reason why he
might have abandoned on motion is that

780
01:15:08.800 --> 01:15:14.920
the ideas that Galleo was developing were
just inconsistent and contradictory with one another.

781
01:15:15.560 --> 01:15:21.239
Having introduced the idea of intermediate motion, Galleo needed to follow through the logic

782
01:15:21.640 --> 01:15:27.439
of this way of thinking and replace
his idea of impressed motion by a different

783
01:15:27.479 --> 01:15:31.760
theory. Had he done so,
he might have reached the conclusion that a

784
01:15:31.800 --> 01:15:36.800
few theorists had already reached in the
Middle Ages, namely that falling bodies have

785
01:15:36.920 --> 01:15:43.800
no absolute rate of fall, but
continue accelerating indefinitely in the absence of air

786
01:15:43.840 --> 01:15:50.560
resistance as gravitational force pulls them downward
in a never ending spiral. This would

787
01:15:50.600 --> 01:15:59.640
have involved abandoning his cherished idea that
heavier bodies necessarily fall faster than lighter bodies,

788
01:16:00.840 --> 01:16:04.880
rather as is of course, true, all bodies would be subject to

789
01:16:04.920 --> 01:16:13.199
the same law of acceleration. But
the fact of the matter is between fifteen

790
01:16:13.239 --> 01:16:15.800
eighty nine and fifteen ninety two,
when he stopped work on on motion,

791
01:16:16.680 --> 01:16:21.640
Galleo was not capable of taking this
step. He stalled, he stopped,

792
01:16:23.079 --> 01:16:29.359
and eventually he gave up. One
problem with this theory is that it implies

793
01:16:29.399 --> 01:16:35.359
that Galileo lacked a sort of intellectual
killer instinct, and frankly, that's not

794
01:16:35.479 --> 01:16:42.000
convincing either. Had Galileo seen a
problem, he would have tried to resolve

795
01:16:42.039 --> 01:16:46.520
it. We just know this based
off of his life. And there's a

796
01:16:46.680 --> 01:16:55.319
third possibility. In fifteen eighty five, Giovanni Battista Benedicti published a new theory

797
01:16:55.359 --> 01:17:00.880
of motion. Like Galileo's theory,
this was archiemti in sort of in its

798
01:17:01.000 --> 01:17:08.600
nature, and very much a critique
of Aristotle's views on natural motion. Like

799
01:17:08.680 --> 01:17:15.039
Galileo's, Benedicti's theory of forced motion
was an impressed force theory, although he

800
01:17:15.079 --> 01:17:20.439
confusingly uses a different term. For
a long time, the standard view has

801
01:17:20.520 --> 01:17:31.439
been that Galileo's argument is so close
to Benedictte's that he just plagiarized it.

802
01:17:31.479 --> 01:17:38.239
But had he. In the course
of On Motion, Galileo does give credit

803
01:17:38.319 --> 01:17:44.520
to two modern authors, boro his
colleague at the University of Pisa and a

804
01:17:44.600 --> 01:17:48.600
Jesuit Pereria, whose book was just
kind of like a standard textbook at the

805
01:17:48.600 --> 01:17:55.880
time. His whole attitude is that
of someone who has profoundly original argument to

806
01:17:56.000 --> 01:18:00.960
sort of add on to those two
gentlemen. Now, of course, in

807
01:18:00.000 --> 01:18:05.640
certain respects, Galleo and Benedicti are
very close in the thought experiment regarding the

808
01:18:05.680 --> 01:18:11.880
two joint bodies. For example,
they basically write the same thing, and

809
01:18:11.960 --> 01:18:20.239
yet Galileo never adopts Benedicti's wording or
his vocabulary. In certain respects, Galleo

810
01:18:20.359 --> 01:18:28.000
and Benedictti differ, Yet Galleo never
engages with Benedictti on these points or argues

811
01:18:28.199 --> 01:18:32.840
why his views are preferable. Indeed, I think On Motion is written as

812
01:18:32.880 --> 01:18:39.039
if Galileo had never heard of Benedicti, nor need he have, for he

813
01:18:39.119 --> 01:18:44.920
has many of the same sources our
Comedees Pereira to draw on. And it's

814
01:18:44.960 --> 01:18:50.479
worth remembering that there was no university
library in sixteenth century Pisa. Books were

815
01:18:50.520 --> 01:18:57.399
expensive and Galleo was poor. He
certainly didn't own many. Benedicti was not

816
01:18:57.439 --> 01:19:00.920
a well known author, and he
had published in Venice. Bon Amiki,

817
01:19:01.199 --> 01:19:06.319
for example, who could afford to
buy books, makes no mention of him

818
01:19:06.479 --> 01:19:13.560
whatsoever in his own vast work on
Motion. The first mention of Benedicti by

819
01:19:13.600 --> 01:19:17.800
a piece and author comes in the
work by Galileo's close friend, but that

820
01:19:17.840 --> 01:19:23.960
doesn't get published until fifteen ninety seven, and it hardly constitutes evidence that Benedicti

821
01:19:24.000 --> 01:19:29.640
was being widely read in Pisa in
fifteen ninety two. This points to a

822
01:19:29.720 --> 01:19:34.520
possible explanation for Galleo's decision to abandon
his work on on Motion. In the

823
01:19:34.520 --> 01:19:39.359
summer of fifteen ninety two, Galileo
spent time in the company of two men

824
01:19:39.479 --> 01:19:45.399
who had certainly been reading Benedicti.
Their names were Giadablo del Monte and Paolo

825
01:19:45.640 --> 01:19:51.760
Sarpi. If he explained his argument
of on Motion to these two gentlemen,

826
01:19:53.760 --> 01:19:57.600
they probably would have immediately told him
that he needed to read Benedicti and that

827
01:19:57.680 --> 01:20:03.840
his core arguments were not original.
And I think honestly this is the correct

828
01:20:03.960 --> 01:20:12.199
explanation for why Galileo abandoned On Motion
around the time he learned of Benedici's existence,

829
01:20:12.720 --> 01:20:16.640
the intellectual enterprise which had produced on
Motion just lost all significance for him.

830
01:20:17.279 --> 01:20:21.560
Galleo abandoned on Motion not because he
was unable to make his experiments come

831
01:20:21.600 --> 01:20:28.039
out right, not because he realized
his argument was incoherent, not or not

832
01:20:28.119 --> 01:20:31.960
only because he had finally heard of
Benedicti, but for one simple reason.

833
01:20:32.800 --> 01:20:36.239
He was now committed to giving an
account of falling bodies on a moving earth.

834
01:20:38.039 --> 01:20:43.000
He had, in other words,
converted to Copernicism, and this meant

835
01:20:43.439 --> 01:20:50.239
he could no longer rely on Archimedes
for his understanding of movement. Now,

836
01:20:50.239 --> 01:20:58.000
from a career perspective, Galileo's first
university appointment had been a failure. He

837
01:20:58.159 --> 01:21:02.760
was paid little five mind, often
for missing lectures and failing the dress code,

838
01:21:03.640 --> 01:21:08.920
and when his father died in fifteen
ninety one, all he left him

839
01:21:09.199 --> 01:21:15.800
were debts. But as we will
see next week, Galileo's biggest achievements in

840
01:21:15.960 --> 01:21:21.600
life actually lie just around the corner.