Give fear no hold on you. Keep sinews loose and senses open, ready at every instant to flow with the rush of action.

We live with our archetypes, but can we live in them?

He had seen too much of the cosmos to have any great faith in man's ability to understand it.

If we knew exactly what to expect throughout the Solar System, we would have no reason to explore it.

There are some ideas so stupid that only intellectuals can believe in them, particularly left-wing intellectuals.

A fanatic is a man who, when he's lost sight of his purpose, redoubles his effort.

My knowledge of the human psyche is as yet imperfect. Certain areas won't yield to computation.