True ideas are those that we can assimilate, validate, corroborate, and verify. False ideas are those that we cannot. That is the practical difference it makes to us to have true ideas; that therefore is the meaning of truth, for it is all that truth is known as.

Man, biologically considered ... is simply the most formidable of all beasts of prey, and, indeed, the only one that preys systematically on its own kind.

To know one thing thoroughly would be to know the universe.

Belief creates the actual fact.

A Beethoven string-quartet is truly, as some one has said, a scraping of horses' tails on cats' bowels, and may be exhaustively described in such terms; but the application of this description in no way precludes the simultaneous applicability of an entirely different description.

The intellectual life of man consists almost wholly in his substitution of conceptual order for the perceptual order in which his experience originally comes.

We are doomed to cling to a life even while we find it unendurable.