Forty-five per cent. of the patients suffer from the real and common mental disease called dementia præcox. The name is a very unhappy one, for the dementia is not always precocious, nor in all cases is there dementia. Unfortunately the disease is too often incurable; even in the best cases, in those that recover, where the outside public would not observe any abnormality, there is always present some defect in the emotional life. The picture presented by the disease is extraordinarily diverse; generally there is some disorder of feeling, frequently delusions and hallucinations. As a rule there is nothing to be found in the brain. Even in cases of a most severe type, lasting for years, an intact brain is not infrequently found _post mortem_. In a few cases only certain slight changes are present which, however, cannot as yet be reduced to any law. To sum up: in round figures a quarter of our insane patients show more or less clearly extensive changes and destruction of the brain, while three-fourths have a brain which seems to be generally unimpaired or at most exhibit such changes as give no explanation of the psychological disturbance. These figures offer the best possible proof that the purely morphological view-point of modern psychiatry leads only very indirectly, if at all, to the understanding of the mental disorder, which is our aim. We must take into account the fact that those mental diseases which show the most marked disturbances of the brain end in death; for this reason the chronic inmates of the asylum form its real population, consisting of some 70 to 80 per cent. of cases of dementia præcox, that is, of patients in whom anatomical changes are practically non-existent. The psychiatry of the future must come to grips with the core of the thing; the path is thus made clear--_it can only be by way of psychology_. Hence in our Zürich clinic we have entirely discarded the anatomical view and turned to the psychological investigation of insanity. As most of our patients suffer from dementia præcox we were naturally concerned with this as our chief problem. * * * * *