Knowledge is the intellectual manipulation of carefully verified observations.

Smoking is indispensable if one has nothing to kiss.

The great question that has never been answered, and which I have not yet been able to answer, despite my thirty years of research into the feminine soul, is 'What does a woman want?'

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

The psychic development of the individual is a short repetition of the course of development of the race.

Homosexuality is assuredly no advantage, but it is nothing to be ashamed of, no vice, no degradation, it cannot be classified as an illness.

A father's death is the most important event, the more heartbreaking and poignant loss in a man's life.