Nicolaus Copernicus

“Finally we shall place the Sun himself at the center of the Universe.”

“Those who know that the consensus of many centuries has sanctioned the conception that the earth remains at rest in the middle of the heavens as its center, would, I reflected, regard it as an insane pronouncement if I made the opposite assertion that the earth moves.”

“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.”

“Therefore, having obtained the opportunity from these sources, I too began to consider the mobility of the earth.”

“Near the sun is the center of the universe.”

“I can easily conceive, most Holy Father, that as soon as some people learn that in this book which I have written concerning the revolutions of the heavenly bodies, I ascribe certain motions to the Earth, they will cry out at once that I and my theory should be rejected.”

“Those things which I am saying now may be obscure, yet they will be made clearer in their proper place.”

“The earth also is spherical, since it presses upon its center from every direction.”

“More stars in the north are seen not to set, while in the south certain stars are no longer seen to rise.”

“Moreover, since the sun remains stationary, whatever appears as a motion of the sun is really due rather to the motion of the earth.”

“The massive bulk of the earth does indeed shrink to insignificance in comparison with the size of the heavens.”

“For it is the duty of an astronomer to compose the history of the celestial motions through careful and expert study.”

“So far as hypotheses are concerned, let no one expect anything certain from astronomy, which cannot furnish it, lest he accept as the truth ideas conceived for another purpose, and depart from this study a greater fool than when he entered it.”

“Accordingly, since nothing prevents the earth from moving, I suggest that we should now consider also whether several motions suit it, so that it can be regarded as one of the planets. For, it is not the center of all the revolutions.”

“Mathematics is written for mathematicians.”

“We regard it as a certainty that the earth, enclosed between poles, is bounded by a spherical surface.”

“I shall now recall to mind that the motion of the heavenly bodies is circular, since the motion appropriate to a sphere is rotation in a circle.”

“Therefore, in the course of the work I have followed this plan: I describe in the first book all the positions of the orbits together with the movements which I ascribe to the Earth, in order that this book might contain, as it were, the general scheme of the universe.”

“Pouring forth its seas everywhere, then, the ocean envelops the earth and fills its deeper chasms.”