De revolutionibus orbium coelestium Earth's axis rigidly to a Sun-centered sphere. The unfortunate consequence was that the terrestrial rotation axis then maintained the same inclination with respect to the Sun as the sphere turned, eliminating the seasons." To explain the seasons, he had to propose a third motion, "an annual contrary conical sweep of the terrestrial axis". It was not until the Great Comet of 1577, which moved as if there were no spheres to crash through, that the idea was challenged. In 1609, Kepler fixed Copernicus' theory by stating that the planets orbit the sun not in circles, but ellipses. Only after Kepler's
Analogy of the sun the Good, we would only be able to see with our physical eyes and not the "mind's eye". The sun bequeaths its light so that we may see the world around us. If the source of light did not exist we would be in the dark and incapable of learning and understanding the true realities that surround us. Incidentally, the metaphor of the sun exemplifies a traditional interrelation between metaphysics and epistemology: interpretations of fundamental existence create—and are created by—ways of knowing. It also neatly sums up two views for which Plato is recognized: his rationalism and his realism (about