I originally studied medicine in order to be a physiologist, but I drifted into psychology and philosophy from a sort of fatality. I never had any philosophic instruction, the first lecture on psychology I ever heard being the first I ever gave.

When a superior intellect and a psychopathic temperament coalesce in the same individual, we have the best possible condition for the kind of effective genius that gets into the biographical dictionaries.

It is your friends who make your world.

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

... A rule of thinking which would absolutely prevent me from acknowledging certain kinds of truth if those ... truths were really there, would be an irrational rule.

If you believe that feeling bad or worrying long enough will change a past or future event, then you are residing on another planet with a different reality system.

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.