Il n'est pas certain que tout soit incertain. (Translation: It is not certain that everything is uncertain.)

When I consider the small span of my life absorbed in the eternity of all time, or the small part of space which I can touch or see engulfed by the infinite immensity of spaces that I know not and that know me not, I am frightened and astonished to see myself here instead of there … now instead of then.

Imagination is the deceptive part in man, the mistress of error and falsehood.

To scorn philosophy is truly to philosophize.

Each man is everything to himself, for with his death everything is dead for him. That is why each of us thinks he is everything to everyone. We must not judge nature by ourselves, but by its own standards.

If a man is not made for God, why is he happy only in God?

Not to be mad is another form of madness