What is truth? I don't know and I'm sorry I brought it up.

Has joy any survival value in the operations of evolution? I suspect that it does; I suspect that the morose and fearful are doomed to quick extinction. Where there is no joy there can be no courage; and without courage all other virtues are useless.

The tragedy of modern war is that the young men die fighting each other - instead of their real enemies back home in the capitals.

I would not sacrifice a single living mesquite tree for any book ever written. One square mile of living desert is worth a hundred 'great books' - and one brave deed is worth a thousand.

A good philosopher is one who does not take ideas seriously.

Little boys love machines; girls adore horses; grown-up men and women like to walk.

Truth is always the enemy of power. And power the enemy of truth.