Nicolaus Copernicus

The earth has a spherical shape, for it is bounded on all sides by the circumference of a circle.

For if the earth should move from west to east, the fixed stars would appear to move from east to west.

The motion of the celestial bodies is uniform, circular, and perpetual, or composed of circular motions.

And if the earth were not to move, such a great diversity of phenomena could not be observed.

So that we may not err, we should always follow the footsteps of the ancients.

To attack me, some people, who know nothing of mathematics, yet dare to pass judgment on these things, on the strength of some passage of Scripture, twisted to their purpose, are now presumptuously attempting to condemn and censure this undertaking of mine.

Perhaps there will be babblers who, although completely ignorant of mathematics, nevertheless dare to pass judgment on these things and, on the strength of some passage in Scripture, twisted to their purpose, will presume to condemn and censure my undertaking.

For these I care nothing, and I shall even despise their judgment as reckless.

So, since there are many places in the Sacred Scriptures where the sun is mentioned as moving, and the earth as standing still, these people will hold that I have contradicted the Holy Scriptures.

But if anyone desires to judge these things not ignorantly but with skill and knowledge, he will find that what I have undertaken is in harmony with the best authorities, and that it is in no way opposed to the holy Scriptures.

For it is the duty of an astronomer to gather by careful and skilled observation the history of the celestial movements, and then to investigate their causes or hypotheses about them, and then to predict these movements correctly.

And so, in the first book, I describe the earth's general position and its various motions, and then I pass to the other planets, showing how their motions are related to the earth's.

The spheres of the planets do not revolve about the earth as their center, but about the sun.

Therefore, we must find a better way to explain the apparent motion of the heavens, which is so complicated and irregular.

For the motions of the planets are so much more orderly and harmonious if they are referred to the sun as the center.

And so, having obtained the opportunity, I now propose to explain the motions of the heavenly bodies, and the order of the universe, with greater certainty than has hitherto been possible.

For it is manifest that the movements of the planets are not uniform, but sometimes faster, sometimes slower, sometimes direct, sometimes retrograde.

The world is not a machine, but a living body, with a soul and a mind.

Knowledge makes a bloody entrance.

I consider it the chief duty of an astronomer to gather the observations of the heavenly bodies, and to explain their motions by hypotheses.