But there are also significant contributions in mathematics. You have Pythagoras, who actually predates these philosophers, and he's most famous, especially to many of us, for his Pythagorean theorem and a lot of mathematics and the foundations of a lot of geometry. But he and his followers, they were actually creating something of a mysticism, of a religion around mathematics, and even a philosophy that would later influence some of the other philosophers that we talk about, especially this ideal of ideal platonic forms. You can imagine, if you're studying perfect right triangles, there's no such thing as a perfect right triangle in the universe. These are ideas that we use in geometry, and other things in the universe are really just approximations of these. But to appreciate the philosophical side of Pythagoras, here are some quotes from him, or quotes ascribed to him. There is geometry in the humming of the strings.