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 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.
James J. Walsh, The Popes and Science (1908)