So look. Tonight, we're switching to the second of the five leading figures we're gonna study this semester, namely Galileo, the others being Descartes, Huygens, Newton, with Kepler we've already dispensed with, at least for the moment. Couple of comments about this. The principle comment I want to make is this is not what science is about, these major figures.

And even tonight, the second half, I'm gonna try to drive home how much, without a huge community assimilating, evaluating, and building off of these people's work, it wouldn't be science. So reading only the leading figures, as if that's what science is, is grossly misleading. And all this course I'll be trying to show you how misleading, including later tonight.

On the other hand these are the five people who pushed things forward. And others did not push it forward nearly as much. So if we're gonna read primary sources and not inundate you reading unbelievable amounts, the natural thing to do is read the figures who push things, pushed the cutting edge forward.

And then pay attention to how people responded and assimilated it. So while this, I hate emphasizing these five people and giving you the impression that's what science is, cuz that's what you think it is from taking undergraduate courses etc. It's only the major figures who make a difference.

Nothing could be further from the truth. That's what philosophy is. The major figures make a difference and people assimilating them and building on them rarely make much difference. It's just a different world with science okay. With out the community, I'll say it the way I like to. Scientific knowledge, the repository of it is in the community at large, not in any one person.

And, you've got to see it from the perspective of the community in order to appreciate it. So far I haven't made much of an effort to do that just because we haven't gotten to a point of seeing anybody assimilate. Okay, that said, there's a stick figure picture of what Newton did.

He took Kepler and Galileo, put them together with the help of Huygens' work on curvilinear motion. In direct negative response to Descartes. So there's a standard picture of Newton's Pernkipia as a response to the prior four in different gradations, where Descartes was the bad guy, Huygens was the person who bridged the gap.

Between Galileo and him and then Kepler was present at, you know, Kepler started the whole thing off. It's interesting, I took the trouble today to look to see which books of Kepler and Galileo that Newton owned and the answer's rather striking, he owned Starry Messenger, and he owned Kepler's Dioptrice which is a reply to the Starry Messenger showing how the telescope really works.

It's the first proper account of telescopes. But he owned them because they were included in a book by Gassendi summarizing the state of astronomy, and he threw those two in. So Newton read both of those in the Latin, but he did not have first editions or original editions of either one.

We know he also read the dialogue, nobody can tell whether he read it in Latin or English. There was an English translation available to him, but I looked at every biographer who's discussed this, and everybody says the same thing. He clearly read Galileo's dialogue, but what the form was in which he read it is unclear.

One last comment about these five. The five are interesting people. They're very different in some respects. Newton and Kepler worked largely in isolation. Galileo constantly had people around him. Actually, Descartes worked somewhat in isolation too, save for his contacts with Marin Mersenne, who arranged for publication of his works.

And Mersenne was quite closely in contact with Galileo as well, bridging the gap between those. Huygens was in the center of science. He was the world's most renowned scientist through much of his adult life, and he lived in Paris because he was the star of the French Academy.

They built it around him, a Dutchman, actually a Protestant Dutchman in a Catholic, French Catholic country. And as I remark in the notes, when I either. All these people had something in common. All of them produced their most important work after the age of 30. Most of them I think after the age of 40.

Which tells you something about the claim that it's only very young people who produce things. I'll just sort of quote myself in the notes, these five people were as hard working people in their scientific, or mathematical endeavors as anybody I've ever encountered. The 16 hour a day, seven day a week type life seems to have been distinctive of all of them except Galileo.

And Galileo, because he was in court all the time, it's a more complicated story. He loved being in court.