Sunday Afternoon: Galileo, Part 2

This is a continuation from last week’s post: Galileo, Part 1.

In Galileo’s time (again, we are talking about the last 1500’s and early 1600’s), science as we know it was still new. It was still common for pure logic and reason alone to be used to discover things about the universe. Galileo was one of the first people to insist on repeatable experimentation as a way to test a hypothesis. This is the way things are done now (when done right, of course), but back then it was completely new. Pure logic and reason led people to believe, for example, that a heavy ball would fall more quickly than a light one. To discover the truth, Galileo wouldn’t sit there and think about it – he’d create an experiment and try it.

It was with this kind of attitude that he looked through his telescope. He did not invent the telescope, but he improved it greatly by matching lenses until he got a setup that worked. He looked at and wrote about the moon (not smooth), Saturn (elongated, he didn’t know why), and Jupiter, which, he discovered after repeated observations, had four moons in orbit around it. Since one of the main objections to the Copernican model was the question of how the Moon could be in orbit around the Earth and the Earth in orbit around something else at the same time, Galileo’s observations of Jupiter’s moons proved that it wasn’t a problem. Jupiter has moons that orbit itself, and Jupiter is in orbit around something.

Galileo presented some of these findings to Pope Paul V in 1611 when he was visiting Rome. The result of that meeting was that the Pope appointed a group of learned priests to examine Galileo’s claims, and they did so. Among other things, they agreed that Jupiter did indeed have satellites.

Again, Galileo found himself in Rome in December of 1615. Pope Paul V had set up a commission “to decide whether Copernican ideas were heretical”[1]. The official conclusion? A sun-centered universe was found to be “foolish and absurd” and “formally heretical”.

On the 26th of February 1616, Cardinal Robert Bellarmine received Galileo in order to tell him of Pope Paul V’s directive that he not “hold or defend” the Copernican model. “If, and only if, Galileo objected to this instruction, he was to be warned by the formal Inquisition.” [1] The representatives of the Inquisition were not fond of Galileo, because of a bitter argument started by a preface in one of his books that named Galileo the discoverer of sunspots, when it was a Jesuit astronomer (Christopher Scheiner) who actually discovered them. (Actually, Scheiner saw them before Galileo, but they were both beaten to that discovery by others.) Unfortunately for Galileo, the Inquisition was present for his meeting with Bellarmine, and the meeting quickly got out of hand. The Inquisition gave him the formal warning, but Bellarmine and Galileo both left without signing any formal declaration. The Pope was informed, but did nothing. Cardinal Bellarmine wrote Galileo a document that said that he was not to “hold or defend” the Copernican system, as if the Inquisition had never issued their warning.

In 1618, Galileo again raised the ire of Jesuits for publicly putting down an account of the significance of comets. He wasn’t shy, because he felt he had the approval of the Pope and Cardinal Bellarmine.

Now, two Popes died in quick succession. After Paul V was Gregory XV, who was succeeded by Urban VIII. Things still looked good for Galileo, though. He was granted six audiences with Pope Urban VIII in 1624. He was awarded and honored in various ways. He was granted permission to write a book on the two world systems – the Ptolemaic and the Copernican. He did this, sent the book in for an imprimatur, which was granted with some conditions. He was required to write a new preface and conclusion to the book, spelling out that the Copernican position was “presented hypothetically”[1].

The book was called Dialogue on the Two Chief World Systems, and it was published. The preface, however, was printed in a different typeface, a technique used to show that the opinion presented was not that of the author. More egregious was that the conclusion that the Copernican position was hypothetical were words given to a character in the Dialogue to say – that character was named “Simplicio”. It didn’t take much to convince Pope Urban VIII that Galileo meant to insult him (and therefore the Church). It didn’t help that Galileo took another dig or two at the Jesuits in the book, too.

The unsigned document from that meeting in 1616 was brought to the angry Pope, who used that evidence to summon Galileo to stand trial for heresy. The observable facts were not the issue here – the heresy was disobeying the directive that the Inquisition was supposed to have given him. When Galileo presented his document from Cardinal Bellarmine, that should have been the end of it, but bringing false charges of heresy did not put the church in a good light. He was asked to confess to something, which he did, since he was 69 years old and his health wasn’t good. He knew that any fight was going to be lost, because the political power was not on his side.

After a vote of 7-3 to convict, Galileo was sentenced to life imprisonment. He served this largely in his own home, and was able to continue his work and his writing. He died peacefully in his sleep in January 1642.

And that, to the best of my knowledge, is what happened. I would like to find out more about that 1615 commission that was appointed by Pope Paul V. What was their reasoning to declare the Copernican model “foolish” and “formally heretical”?


1Science: A History 1543 – 2001 by John Gribbin, 2002, ISBN 9780713995039.

2Triumph: The Power and Glory of the Catholic Church, A 2000 Year History by H. W. Crocker III, 2001, ISBN 0761529241.

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3 Responses to Sunday Afternoon: Galileo, Part 2

  1. Jesse Willis says:

    Excellent postage!

  2. March Hare says:

    Hi Scott–

    Found you through Julie D.

    FWIW, I took several courses on The History of Science at Cal as an undergrad and Galileo’s trial was discussed. As I recall, the feeling in the mid-’70’s was that the cause of this brouhaha was professional jealousy between the Jesuits (the leading intellects of the Church) and Galileo. He basically pissed off the wrong people. If memory serves, Copernicus was a Dominican, which also piqued the Jesuits’ pride. (As a Catholic with some experience with Jesuits, I could see it. :)

    My prof pointed out that the trial was about Galileo’s ~disobedience~, not his science. Had he been a little more humble in writing “Two Worlds,” he never would have gone to trial.

    The Bancroft Library at Cal has an early edition of the treatise, which our class got to see. Pretty special for undergrads!

  3. Scott D says:

    Hello, March Hare,

    Wow, seeing that treatise must’ve been something else.

    I think we’re in total agreement here. I did not know that Copernicus was Dominican, though, but I did know that Galileo and the Jesuits were not getting along, and that Galileo seemed to have no problem at all with making them angry because he felt he was protected by the folks above them. When that protection disappeared – trial time. They didn’t like him, and they had him.

    But the point that is most important? This had nothing to do with the science.

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