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

For what could be more beautiful than the heavens which contain all beautiful things.

To know that we know what we know, and to know that we do not know what we do not know, that is true knowledge.

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.

The scorn which I had reason to fear on account of the novelty and unconventionality of my opinion almost induced me to abandon completely the work which I had undertaken. . . . Astronomy is written for astronomers. To them my work too will seem, unless I am mistaken, to make some contribution.

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

Of all things visible, the highest is the heaven of the fixed stars.