There are many ideas in which our faith is sustained chiefly by the knowledge that everyone about us also believes them. Belief on such ground has commonly been said to be due to imitation or suggestion. These do play a large part in determining all our thinking, but I can see no reason why they should be more operative in causing the crowd-mind than in other social situations. In fact, the distinctive phenomena which I have called crowd-ideas clearly show that other causes are at work. Among civilized people, social relationships make severe demands upon the individual. Primitive impulses, unchecked eroticism, tendencies to perversions, and antisocial demands of the ego which are in us all, are constantly inhibited, resisted, controlled and diverted to socially acceptable ends. The savage in us is "repressed," his demands are so habitually denied that we learn to keep him down, for the most part, without conscious effort. We simply cease to pay attention to his gnawing desires. We become decently respectable members of society largely at the expense of our aboriginal nature. But the primitive in us does not really die. It asserts itself harmlessly in dreams. Psychoanalysis has revealed the fact that every dream is the realization of some desire, usually hidden from our conscious thought by our habitual repression. For this reason the dream work consists of symbols. The great achievement of Freud is the technique which enables the analyst to interpret this symbolism so that his own unconscious thought and desire are made known to the subject. The dream is harmless and is normally utilized by the unconscious ego because during sleep we cannot move. If one actually did the things he dreamed, a thing which happens in various somnambulisms, the dream would become anything but harmless. Every psychosis is really a dramatized dream of this sort. Now as it is the social which demands the repression of our primitive impulses, it is to be expected that the unconscious would on certain occasions make use of this same social in order to realize its primitive desires. There are certain mental abnormalities, such as dementia præcox, in which the individual behaves in a wholly antisocial manner, simply withdrawing into himself. _In the crowd the primitive ego achieves its wish by actually gaining the assent and support of a section of society. The immediate social environment is all pulled in the same direction as the unconscious desire._ A similar unconscious impulse motivates each member of the crowd. It is as if all at once an unspoken agreement were entered into whereby each member might let himself go, on condition that he approved the same thing in all the rest. Of course such a thing cannot happen consciously. Our normal social consciousness would cause us each to resist, let us say, an exhibition of cruelty--in our neighbors, and also in ourselves. The impulse must therefore be disguised.