“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.”

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

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

The earth together with its surrounding waters must in fact have such a shape as its shadow reveals, for its eclipses the moon with the arc of a perfect circle.

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

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

I often considered whether there could perhaps be found a more reasonable arrangement of circles.

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

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

Near the sun is the center of the universe.

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

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

Let whoever can do so deceive me, he will never bring it about that I am nothing, so long as I continue to think I am something.

I was not always strong. But I was always brave. And to be brave is strong enough.

Am I so tied to a body and senses that I am incapable of existing without them?

Being real is effortless, my child, because it means we’ve embraced exactly who we are.

To become self-educated you should condemn yourself for all those things that you would criticize others.

Three things are necessary for the salvation of man: to know what he ought to believe; to know what he ought to desire; and to know what he ought to do.

Toil and risk are the price of glory, but it is a lovely thing to live with courage and die leaving an everlasting fame.

When my casket is being carried to the grave, leave my hands hanging outside. For empty-handed, I came into this world and empty-handed, I shall go!