Dr. Waelder has selected the collective psychoses for special investigation because of their importance in provoking and sustaining war. He discusses the topic from the point of view of promoting an understanding of the causation and evolution of these collective psychoses, rather than with the hope of discovering a sterilisatio magna to prevent their future occurrence.

There is an apparent contradiction implicit in the term "collective psychoses", since the outstanding characteristic of the psychotic is his withdrawal from collective human activities, and his partial or total lack of participation in the social life, the thoughts, and the feelings of other people. How then can a group be subject to a psychosis when the sufferers from this common malady not only do not lose contact with each other, but are the more closely bound to each other because of it? Such individuals are not, psychiatrically speaking, mentally ill, since they behave in quite a normal fashion so long as the boundaries of their collective psychosis are not infringed upon. On the other hand, the ideational content of a collective psychosis is impervious to logic, and is quite comparable to the systematized delusions of a true psychosis. It seems paradoxical that only normal people fall prey to a collective psychosis precisely because they establish contacts easily and seek to avoid a break with society. True psychotics, on the other hand, take cover behind their own narcissism, run no risk of being affected by collective psychoses, and rarely abandon their private world of fantasy in favor of the imaginary collective world of socialized man. It