When some of us older members of this society began to study mental diseases, we had a very simple classification. There were mania, melancholia, monomania and dementia, as the four main groups. Additions and modifications were made in due time, and names were changed. The toxic and infectious psychoses and those caused by organic lesions of the brain, such as dementia paralytica, came to be more fully recognized. Then, of course, there were the psychoneuroses, such as hysteria and neurasthenia; finally, there was the great group of the idiocies and imbecilities. The merits of this scheme were its simplicity and that it was in accord with facts.
When I say that it was in accord with facts I refer especially to the distinction which it drew between mania and melancholia. These two were separate diseases, the antitheses of each other. No one in those days would have thought of denying