The consequences of a plethora of half-digested theoretical knowledge are deplorable.

The factor in human life provocative of a noble discontent is the gradual emergence of a sense of criticism, founded upon appreciation of beauty, and of intellectual distinction, and of duty.

Each human being is a more complex structure than any social system to which he belongs.

The worst that happened to men of science was that Galileo suffered an honorable detention and a mild reproof, before dying peacefully in his bed.

What is morality in any given time or place? It is what the majority then and there happen to like and immorality is what they dislike.

The vitality of thought is in adventure. Ideas won't keep. Something must be done about them. When the idea is new, its custodians have fervor, live for it, and if need be, die for it.

Imagination is not to be divorced from the facts. It is a way of illuminating the facts.