A sense of humour is the only divine quality of man

Our moral virtues benefit mainly other people; intellectual virtues, on the other hand, benefit primarily ourselves; therefore the former make us universally popular, the latter unpopular.

Just as the largest library, badly arranged, is not so useful as a very moderate one that is well arranged, so the greatest amount of knowledge, if not elaborated by our own thoughts, is worth much less than a far smaller volume that has been abundantly and repeatedly thought over.

Genius and madness have something in common: both live in a world that is different from that which exists for everyone else.

To free a man from error is to give, not to take away. Knowledge that a thing is false is a truth. Error always does harm; sooner or later it will bring mischief to the man who harbors it.

If we were not all so interested in ourselves, life would be so uninteresting that none of us would be able to endure it.

It is a clumsy experiment to make; for it involves the destruction of the very consciousness which puts the question and awaits the answer.