A new question has arisen in modern man's mind, the question, namely, whether life is worth living...No sensible answer can be given to the question...because the question does not make any sense.

Man's biological weakness is the condition of human culture.

Free man is by necessity insecure, thinking man by necessity uncertain.

To love one person productively means to be related to his human core, to him as representing mankind. Love for one individual, in so far as it is divorced from love for man, can refer only to the superficial and to the accidental; of necessity it remains shallow.

Man is born as a freak of nature, being within nature and yet transcending it. He has to find principles of action and decision-making which replace the principles of instincts.

Sleep is often the only occasion in which man cannot silence his conscience; we forget what we knew in our dream.

Man is the only animal who does not feel at home in nature, who can feel evicted from paradise, the only animal for whom his own existence is a problem that he has to solve and from which he cannot escape. He cannot go back to the prehuman state of harmony with nature, and he does not know where he will arrive if he goes forward. Man's existential contradiction results in a state of constant disequilibrium. This disequilibrium distinguishes him from the animal, which lives, as it were, in harmony with nature.

What is it that distinguishes man from animals? It is not his upright posture.

The two most far-reaching critical theories at the beginning of the latest phase of industrial society were those of Marx and Freud. Marx showed the moving powers and the conflicts in the social-historical process. Freud aimed at the critical uncovering of the inner conflicts. Both worked for the liberation of man, even though Marx's concept was more comprehensive and less time-bound than Freud's.