The earth together with its surrounding waters must in fact have such a shape as its shadow reveals, for it eclipses the moon with the arc of a perfect circle.
Nicolaus CopernicusMoreover, since the sun remains stationary, whatever appears as a motion of the sun is really due rather to the motion of the earth.
Nicolaus CopernicusYet the widespread planetary theories, advanced by Ptolemy and most other astronomers, although consistent with the numerical data, seemed likewise to present no small difficulty. For these theories were not adequate unless they also conceived certain equalizing circles, which made the planet appear to move at all times with uniform velocity neither on its deferent sphere nor about its own epicycle's center.
Nicolaus Copernicus