A person cannot make another happy, but he can make him unhappy. This is the main reason why there is more unhappiness than happiness in the world.

Self-respect is to the soul as oxygen is to the body. Deprive a person of oxygen, and you kill his body; deprive him of self-respect and you kill his spirit.

Knowledge is gained by learning; trust by doubt; skill by practice; and love by love.

Whenever masses of people, especially educated people, know something - and when what they know is something they greatly fear because they believe it affects virtually everything they do or want to do - then most likely we stand in the presence of a vast falsehood.

Doubt is to certainty as neurosis is to psychosis. The neurotic is in doubt and has fears about persons and things; the psychotic has convictions and makes claims about them. In short, the neurotic has problems, the psychotic has solutions.

Formerly, when religion was strong and science weak, men mistook magic for medicine; now, when science is strong and religion weak, men mistake medicine for magic.

Permissiveness is the principle of treating children as if they were adults; and the tactic of making sure they never reach that stage.