This introduction seeks to put before the reader a general sketch of the history of psychopathology from its beginnings to the position which it held in 1912, in order that he may be able to appreciate the place in the subject of the principles described in this book. It therefore attempts to cover a wider field than is proper to an introduction, and for this reason the uninstructed layman will probably find it more intelligible and useful if it is read after rather than before the book.

DEVELOPMENT OF PSYGHOPATHOLOGY PRIOR TO JANET

Psychopathology, the science which attempts to explain the problems of mental disorder by psychological principles and laws, is of comparatively recent growth, and can hardly be said to have existed before the last quarter of the nineteenth century. The remarkable phenomena produced by Mesmer and the other ‘magnetisers’ had aroused a widespread interest a hundred years earlier, and later investigators had demonstrated that these phenomena were due, not to the magnets, but to the suggestions communicated by the operator. These ‘suggestions’ were clearly causes of a psychological order, and it was therefore known that psychological causes were capable of bringing about definite changes in mind and body. Until the time of Gharcot (1825–93), however, this conception had not been applied to the problem of disease, and we owe to that investigator the first formulation of the view that certain disorders were due simply to the action of ‘ideas’.