Nicolaus Copernicus

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

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.

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

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

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.

Although all the good arts serve to draw man's mind away from vices and lead it toward better things, this function can be more fully performed by this art, which also provides extraordinary intellectual pleasure.

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.

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.

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

I am aware that a philosopher's ideas are not subject to the judgment of ordinary persons, because it is his endeavour to seek the truth in all things, to the extent permitted to human reason by God.

So, influenced by these advisors and this hope, I have at length allowed my friends to publish the work, as they had long besought me to do.