He is unworthy of the name of man who is ignorant of the fact that the diagonal of a square is incommensurable with its side.

For a man to conquer himself is the first and noblest of all victories.

Knowledge becomes evil if the aim be not virtuous.

The true lover of knowledge naturally strives for truth, and is not content with common opinion, but soars with undimmed and unwearied passion till he grasps the essential nature of things.

Rhythm and melody enter into the soul of the well-instructed youth and produce there a certain mental harmony hardly obtainable in any other way. . . . thus music, too, is concerned with the principles of love in their application to harmony and rhythm.

We are like people looking for something they have in their hands all the time; we're looking in all directions except at the thing we want, which is probably why we haven't found it.

The philosopher whose dealings are with divine order himself acquires the characteristics of order and divinity.