Pathology has made us acquainted with a great number of states in which the boundary lines between the ego and the external world become uncertain or in which they are actually drawn incorrectly. There are cases in which parts of a person's own body, even portions of his own mental life - his perceptions, thoughts and feelings -, appear alien to him and as not belonging to his ego; there are other cases in which he ascribes to the external world things that clearly originate in his own ego and that ought to be acknowledged by it.

A collection to which nothing can be added and from which nothing can be removed is, in fact, dead!

Thinking in pictures is, therefore, only a very incomplete form of becoming conscious. In some way, too, it stands nearer to unconscious processes than does thinking in words, and it is unquestionably older than the latter both ontogenetically and phylogenetically.

In every age immorality has found no less support in religion than morality has. If the achievements of religion in respect to man's happiness, susceptibility to culture and moral control are no better than this, the question cannot but arise whether we are not overrating its necessity for mankind, and whether we do wisely in basing our cultural demands upon it.

America is a mistake, a giant mistake.

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.

The facts which have caused us to believe in the dominance of the pleasure principle in mental life also find expression in the hypothesis that the mental apparatus endeavours to keep the quantity of excitation present in it as low as possible or at least to keep it constant.