A man like me cannot live without a hobby-horse, a consuming passion - in Schiller's words a tyrant. I have found my tyrant, and in his service I know no limits. My tyrant is psychology. It has always been my distant, beckoning goal and now since I have hit upon the neuroses, it has come so much the nearer.

I am actually not at all a man of science, not an observer, not an experimenter, not a thinker. I am by temperament nothing but a conquistador

Conscience is the internal perception of the rejection of a particular wish operating within us.

Beauty has no obvious use; nor is there any clear cultural necessity for it. Yet civilization could not do without it.

We are never so defensless against suffering as when we love.

Were we fully to understand the reasons for other people's behavior, it would all make sense.

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.