If we are to keep our flock at the highest pitch of excellence, there should be as many unions of the best of both sexes, and as few of the inferior as possible, and that only the offspring of the better unions should be kept.

Between knowledge of what really exists and ignorance of what does not exist lies the domain of opinion. It is more obscure than knowledge, but clearer than ignorance.

Then may we not fairly plead in reply that our 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 with the mental faculty fitted to do so, that is, with the faculty which is akin to reality, and which approaches and unites with it, and begets intelligence and truth as children, and is only released from travail when it has thus reached knowledge and true life and satisfaction?

He who does not desire power is fit to hold it.

He who has knowledge of the just and the good and beautiful ... will not, when in earnest, write them in ink.

No intelligent man will ever be so bold as to put into language those things which his reason has contemplated.

He who can properly define and divide is to be considered a god.