It is, I think, unnecessary to apologise for the increase in size. If psychology is to be taken seriously, its prob lems must nowadays be treated in some detail. Besides, the T ext-book aims, within its limits and upon the elemen tary level, at systematic completeness; it is not a digest or redaction of a larger work, to which the student may be referred for further information. I could wish, remem bering some of the criticism called forth by the Outline, that I had a fully elaborated Systematic Psychology to fall back upon; but I am inclined to believe that, from the student's point of View, a text written expressly for the class-room is more satisfactory than the simplified version of a book written primarily for psychologists.