A large number of patients have impulses to perform certain useless, bizarre, and even dangerous acts, not generally, however, very important acts; when it is a question of dangerous acts the patient is apt to feel himself drawn towards them rather than actually impelled to accomplish them. The mechanism of the impulsion is not always the same. Sometimes it is analogous to that of suggestion; at other times the impulsion appears to develop subconsciously, entering the field of a retracted consciousness too late to be easily controlled. Beyond these and other causes there is, Janet believes, a mental disposition common among the obsessed and impulsive which plays an important part in many cases.

To illustrate the factor in question five cases are briefly narrated, all in young women. One is a case of periodical dipsomania, the attacks occurring at intervals of a few weeks or months and being followed by repentance and despair; another of the rarer impulsion to eat, the patient feeling a constant need of support; the third of dromomania, or the mania for walking, the patient not beginning to feel at her ease until she has walked over forty kilometres along a public highway, so that no sanatorium can be found sufficiently spacious for her; the fourth must tear out her hairs one by one and eat them, and has thus lost a luxuriant head of hair; the fifth is never happy unless she tortures and wounds and bruises herself. These impulsions, though apparently different, have common clinical characteristics. They are periodic and irresistible, while their satisfaction is followed by good but useless resolutions.

In all these cases, the essential part of the psycholeptic crisis, Janet believes, is played, not by the impulsions, but by the period of depression and the sense of incompleteness which are in every case found to precede the crisis and to be expressed in the same terms and in the same metaphors by every patient. The impulsion is merely a way of escape from this intolerable state of mind. Thus the girl who wounds herself is far from having any desire for self-mortification. “It is my parents who believe that,” she says, “but it is absurd. It would be a mortification if it brought any suffering, but I enjoy this suffering; it gives me back my mind; it prevents my thoughts from stopping; what would one not do to attain such happiness?” The other patients bear testimony to a similar effect.

These absurd acts are passionately sought, not from any insane notions, but because they really are stimulating, and really do tend to dispel the depression from which the patient is suffering. So far, therefore, from being truly morbid, these impulsions are rational therapeutic measures, the mistake being that the patient employs them in excess, and also fails to realise that there are other equally effective methods of obtaining relief. We must always remember, Janet concludes, that the cause of the impulsion is in the underlying attack of depression, and it is the latter which we have to combat, for the psychological analysis of pathological symptoms is not only interesting from a scientific point of view, but of great importance in its practical application.