I am aware that a philosopher’s ideas are not subject to the judgment of ordinary persons.

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.

Through steady observation, arranged by God’s wisdom, who would not be guided to admire the Builder who creates all.

To know the mighty works of God, all this must be a pleasing and acceptable mode of worship to the Most High.

The Universe, wrought for us by a supremely good and orderly Creator.

The center of the earth is not the center of the universe, but only of gravity and of the lunar sphere.

The earth together with its circumjacent elements performs a complete rotation on its fixed poles in a daily motion.

For every apparent change in respect of position is due to motion of the object observed, or of the observer, or indeed to an unequal change of both.

Nor is it necessary that these hypotheses should be true, nor indeed even probable.

Gravity is merely a certain natural inclination with which parts are imbued by the architect of all things.

Mathematics is written for mathematicians.

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

There may be babblers who dare to condemn my hypothesis. I value them not.

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.

In so many and such important ways, then, do the planets bear witness to the earth’s mobility.

For a traveler going from any place toward the north, that pole of the daily rotation gradually climbs higher, while the opposite pole drops down an equal amount.

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

I knew that mathematicians by no means agree in their investigation thereof.

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

Yet if anyone believes that the earth rotates, surely he will hold that its motion is natural, not violent.

There is no one center of all the celestial circles or spheres.

Yet the widespread planetary theories seemed likewise to present no small difficulty.

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

We find then in this arrangement an admirable harmony of the world.”

The first and highest of all is the sphere of the fixed stars, which comprehends itself and all things, and is accordingly immovable.

I feel no shame in asserting that this whole region engirdled by the moon, and the center of the earth, traverse this grand circle amid the rest of the planets in an annual revolution around the sun. Near the sun is the center of the universe.

In the midst of all dwells the Sun. For who could set this luminary in another or better place in this most glorious temple, than whence he can at one and the same time brighten the whole.

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

In the first book I shall describe all the positions of the spheres, along with the motions which I attribute to the Earth, so that the book will contain as it were the general structure of the universe.

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

All the spheres revolve about the sun as their mid-point, and therefore the sun is the center of the universe.

It is proper for an astronomer to establish a record of the motions of the heavens with diligent and skilful observations, and then to think out and construct laws for them.

Since different hypotheses are sometimes available to explain one and the same motion. An astronomer will prefer to seize on the one which is easiest to grasp.

If then the Earth also performs other motions, they must necessarily be like those which are similarly apparent in many external bodies in which we find an annual orbit.

Since nothing stands in the way of the movability of the earth, I believe we must now investigate whether it also has several motions, so that it can be considered one of the planets.

The strongest affection, I think, promote the studies concerned with the most beautiful objects . the universe’s divine revolutions, the stars’ motions, sizes, distances.

At rest, however, in the middle of everything is the sun.

Trismegistus calls it a ‘visible God’; Sophocles’ Electra, ‘that which gazes upon all things’. And so the sun governs the family of stars which wheel around.

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 motion of the earth can unquestionably produce the impression that the entire universe is rotating.

In first place we must observe that the universe is spherical.

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.

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

Astronomy is written for astronomers. To them my work too will seem, unless I am mistaken, to make some contribution.

So if the worth of the arts were measured by the matter with which they deal, this art-which some call astronomy, others astrology.

What appears to us as motions of the sun arise not from its motion but from the motion of the earth and our sphere, with which we revolve about the sun like any other planet. The earth has, then, more than one motion.

Moreover, why Saturn, Jupiter, and Mars, when they rise in the evening, appear greater than when they disappear and reappear with the sun.

Let no one expect anything certain from astronomy, which cannot furnish it, lest he accept as the truth ideas conceived for another purpose.

If the motions of the other planets were added to the rotation of the earth and calculated as for the revolution of that planet … it so bound together both the order and magnitude of all the planets and the spheres and the heaven itself, that in no single part could one thing be altered without confusion among the other parts and in all the universe.

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

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

Every light has its shadow, and every shadow hath a succeeding morning.

For I am not so enamoured of my own opinions that I disregard what others may think of them.

Nations are not ruined by one act of violence.

Although all the good arts serve to draw man’s mind toward better things, this function can be more fully performed by this art.

I have at length allowed my friends to publish the work, as they had long besought me to do.

Not a few other very eminent and scholarly men made the same request, urging that I should no longer through fear refuse to give out my work for the common benefit of students of Mathematics.

I hold that completely erroneous views should be shunned.

But we should rather follow the wisdom of nature.

I took upon myself the task of re-reading the books of all the philosophers which I could obtain, to seek out whether any one had ever conjectured that the motions of the spheres of the universe were other than they supposed who taught mathematics in the schools.