Today's rebel is tomorrow's tyrant.

It is good a philosopher should remind himself, now and then, that he is a particle pontificating on infinity.

A great civilization is not conquered from without until it has destroyed itself from within.

If you have character, endeavor, personality, courage and the capacity for concentrated labor, you will do what is your destiny – and, perhaps, even do it well.

No man who is in a hurry is quite civilised.

Man, not the earth, makes civilization.

The laws of biology are the fundamental lessons of history.