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.

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.

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

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.

First of all, we must note that the universe is spherical.