Loneliness and darkness have just robbed me of my valuables.

The view is often defended that sciences should be built up on clear and sharply defined basal concepts. In actual fact no science, not even the most exact, begins with such definitions. The true beginning of scientific activity consists rather in describing phenomena and then in proceeding to group, classify and correlate them.

Our unconscious, then, does not believe in its own death; it behaves as if it were immortal. It knows nothing that is negative; in it contradictories coincide. This may be the secret of heroism.

The communal life of human beings had . . . a two-fold foundation: the compulsion to work, which was created by external necessity, and the power of love.

Where does a thought go when it's forgotten?

We are so made that we can derive intense enjoyment only from a contrast.

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