Concerning the factors of silence, solitude and darkness, we can only say that they are actually elements in the production of the infantile anxiety from which the majority of human beings have never become quite free.

A strong egoism is a protection against disease, but in the last resort we must begin to love in order that we may not fall ill, and must fall ill if, in consequence of frustration, we cannot love.

The whole life of instinct serves the one end of bringing about death.

The behavior of a human being in sexual matters is often a prototype for the whole of his other modes of reaction in life.

We must love or we grow ill.

In the development of mankind as a whole, just as in individuals, love alone acts as the civilizing factor in the sense that it brings a change from egoism to altruism.

The division of the psychical into what is conscious and what is unconscious is the fundamental premise of psycho-analysis; and it alone makes it possible for psycho-analysis to understand the pathological processes in mental life, which are as common as they are important, and to find a place for them in the framework of science.