No one who has seen a baby sinking back satiated from the breast and falling asleep with flushed cheeks and a blissful smile can escape the reflection that this picture persists as a prototype of the expression of sexual satisfaction in later life.

The voice of reason is small, but very persistent.

I consider it a good rule for letter-writing to leave unmentioned what the recipient already knows, and instead tell him something new.

The more the fruits of knowledge become accessible to men, the more widespread is the decline of religious belief.

Civilized society is perpetually menaced with disintegration through this primary hostility of men towards one another.

The price we pay for our advance in civilization is a loss of happiness through the heightening of the sense of guilt.

It often seems that the poet's derisive comment is not unjustified when he says of the philosopher: “With his nightcaps and the tatters of his dressing-gown he patches the gaps in the structure of the universe.