Imagination is more important than knowledge.

Against that positivism which stops at phenomena, saying 'there are only facts,' I would say: No, it is precisely facts that do not exist, only interpretations.

Every acquisition, every step forward in knowledge is the result of courage, of severity toward oneself, of cleanliness with respect to oneself.

Partial knowledge is more triumphant than complete knowledge; it takes things to be simpler than they are, and so makes its theory more popular and convincing.

No honey is sweeter than that of knowledge.

The man of knowledge must be able not only to love his enemies but also to hate his friends.