Great minds think for themselves.

Procrastination is hardly more evil than grasping impatience.

We ourselves introduce that order and regularity in the appearance which we entitle "nature". We could never find them in appearances had we not ourselves, by the nature of our own mind, originally set them there.

For how is it possible, says that acute man, that when a concept is given me, I can go beyond it and connect with it another which is not contained in it, in such a manner as if that latter necessarily belonged to the former?

But only he who, himself enlightened, is not afraid of shadows.

Both love of mankind, and respect for their rights are duties; the former however is only a conditional, the latter an unconditional, purely imperative duty, which he must be perfectly certain not to have transgressed who would give himself up to the secret emotions arising from benevolence.

Maturity is having the courage to use one's own intelligence!