This work is the fruit of three years' experimental labor and clinical observation. In view of the difficulty and magnitude of the material, my work cannot and will not lay any claims either to perfection of treatment or to perfect certainty of conclusions and statements; on the contrary, it unites in itself all the disadvantages of eclecticism, which perhaps to many a reader will seem so peculiar that he will call my work rather a confession of faith than a scientific book.—Peu importe! What is of chief concern is that I may succeed in showing my readers how, by certain psychological investigations, I reached certain views, which I deem fit for the stimulation of the problems of the individual psychological basis of dementia præcox in a new and fruitful direction.