To be without some of the things you want is an indispensable part of happiness.

Religion is something left over from the infancy of our intelligence, it will fade away as we adopt reason and science as our guidelines.

The greatest challenge to any thinker is stating the problem in a way that will allow a solution.

Every isolated passion, is, in isolation, insane; sanity may be defined as synthesis of insanities. Every dominant passion generates a dominant fear, the fear of its non-fulfillment. Every dominant fear generates a nightmare, sometimes in form of explicit and conscious fanaticism, sometimes in paralyzing timidity, sometimes in an unconscious or subconscious terror which finds expression only in dreams. The man who wishes to preserve sanity in a dangerous world should summon in his own mind a parliament of fears, in which each in turn is voted absurd by all the others.

A world full of happiness is not beyond human power to create; the obstacles imposed by inanimate nature are not insuperable. The real obstacles lie in the heart of man, and the cure for these is a firm hope, informed and fortified by thought.

Something of the hermit's temper is an essential element in many forms of excellence, since it enables men to resist the lure of popularity, to pursue important work in spite of general indifference or hostility, and arrive at opinions which are opposed to prevalent errors.

... mathematical knowledge ... is, in fact, merely verbal knowledge. "3" means "2+1", and "4" means "3+1". Hence it follows (though the proof is long) that "4" means the same as "2+2". Thus mathematical knowledge ceases to be mysterious.