Sigmund Freud

Knowledge is the intellectual manipulation of carefully verified observations.

Men are strong only so long as they represent a strong idea. They become powerless when they oppose it.

Thought is action in rehearsal.

It is always possible to bind together a considerable number of people in love, so long as there are other people left over to receive the manifestations of their aggression.

We are threatened with suffering from three directions: from our own body, which is doomed to decay and dissolution and which cannot even do without pain and anxiety as warning signals; from the external world, which may rage against us with overwhelming and merciless forces of destruction; and finally from our relations to other men. The suffering which comes from this last source is perhaps more painful than any other.

The mind is an iceberg - it floats with only one-seventh of its bulk above water.

When the wayfarer whistles in the dark, he may be disavowing his timidity, but he does not see any the more clearly for doing so.

Just as a cautious businessman avoids investing all his capital in one concern, so wisdom would probably admonish us also not to anticipate all our happiness from one quarter alone.

What do women want, my God, what do they want? What does a woman want.

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?'