It is with regard to astronomy, of course, that Dante has given us the most convincing evidence of his knowledge of science, his interest in nature and natural phenomena, his questioning spirit in nature study, and the wonderful anticipations of his generation with regard to knowledge that has usually been supposed to have been hidden from them. The stars appealed to his poetic spirit, and then besides, his great poem occupied itself with all the visible universe, and especially with the parts outside this world. Professor Kuhns has said: "One may confidently assert that no such perfect lines descriptive of the stars have ever been written. Shakespeare and others can furnish famous passages, but none, I think, equal to those of Dante. They have all the quality of his art--truth, clearness, possessing the power of touching deeply the imagination, yet terse and compact, containing not a word too much. We see the stars at all hours of the night, in all degrees of brilliancy, fading away at the approach of dawn, gradually appearing as twilight comes on, shining with splendor on a moonless night, keenly sparkling after the winds have cleared the atmosphere, or eclipsed by the greater effulgence of the moon. The motion of the constellations about the pole is referred to, those which are nearest to it never setting beneath the horizon." It is often thought that the proper idea of the explanation of the Milky Way was quite modern. Dante, however, discusses in his Convito the theories of it that had been suggested up to his time, and then gives his own {351} views, which he confesses are founded on Aristotle, but which are evidently the result also of his own thinking. Pythagoras, he said, attributed it to the scorching heat of the sun, as if somehow this left a trace of itself even after the sun had sunk. Other Greek philosophers, as for example Anaxagoras and Democritus, explained it as a reflection of the light of the sun which still found its way even though that luminary had passed from sight. Dante himself says that, following Aristotle, he cannot help but think that the Milky Way is composed of a multitude of minute stars which are gathered very closely together in this particular part of the heavens, and which are so small that they cannot be distinguished from one another, though their light causes that special white luminosity which we call the Milky Way. This explanation is the true one, only that the apparent smallness of the stars are due to their distance, and not to their actual minuteness of size.