Combinatory play seems to be the essential feature in productive thought.

Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world.

Science can only ascertain what is, but not what should be, and outside of its domain value judgements of all kinds remain necessary.

Everybody acts not only under external compulsion but also in accordance with inner necessity.

Do you believe in immortality? No, and one life is enough for me.

The important thing is to never stop questioning. Never lose a holy curiosity.

I find it difficult to believe that I belong to such an idiotic, rotten species - the species that actually boasts of its freedom of will, heroism on command, senseless violence, and all of the loathsome nonsense that goes by the name of patriotism.