Nicolaus Copernicus

I have been so long in preparing this work that I have almost despaired of publishing it.

When, therefore, I had long considered the uncertainty of the traditional mathematical doctrines concerning the order of the spheres of the universe, I began to be annoyed that no more accurate explanation of the movements of the world-machine, set in order for our sake by the best and most orderly Workman of all, was agreed upon by the philosophers.

For it is not necessary that hypotheses should be true, or even probable; it is enough if they provide a calculus which agrees with the observations.

For I am convinced that the world is a single, unified system, and that all its parts are interrelated.

Therefore, we should not be surprised if the earth moves, for it is a planet, and all planets move.

The Sun, the Moon, and the Earth, are all parts of one great system.

It is the duty of a good astronomer to seek for truth in all things, and to follow it wherever it may lead.

For what could be more beautiful than the heavens, which contain all things of beauty?

I confess that I have been led to conceive of a different arrangement of the spheres of the universe from that of the ancient astronomers.

It is enough if the hypotheses save the phenomena.

For the motion of the earth is not a simple motion, but a composite of many motions.

The Sun, the Moon, and the five wandering stars are all governed by the same laws.

Therefore, let us not be afraid to follow truth wherever it may lead us, even if it contradicts our preconceived notions.

For it is not the magnitude of the stars, but the magnitude of their distance from us, that causes them to appear small.

The universe is a harmonious system, and all its parts are in perfect accord.

For the Earth, which is a planet, must therefore move in a circle around the Sun.

The movements of the heavens are an ordered dance, and the Earth is a participant in this dance.

For I have found that the motions of the planets are more regular and orderly if the Earth is assumed to move.

The Sun is the center of the universe, and all the planets revolve around it.

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