Psychology as he does riders in Euclid. It is true that there are students who cannot advance so far from lack of natural endowment. But even for them a treatment full enough to be interesting and so rememberable is better than arid and dogmatic statements which have to be read over feverishly the day before an examination in order that they may not slip out of the mind. Certainly the teacher who needs Psychology for educational purposes would do much better to leave the subject alone altogether than to learn it in a merely external way.<br><br>My greatest debt here as elsewhere is to my teacher, Professor James Ward. In treating the special sensations I have found the fourth volume of Professor Foster's Text-Book of Physiology very useful. The special chapters on Light-Sensation and Sound-Sensation are abbreviated and adapted with modifications from Professor Ebbinghaus' Grundzüge der Psychologie. In general I have found much help in the writings of James, Baldwin, Ladd, Royce, and Lloyd Morgan. My proofs have been read by Mr. J. Welton, Lecturer in Education in the Yorkshire College, Victoria University, by Professor J. S. Mackenzie, of the University College of South Wales, and by Mr. M. C. W. Irvine, Mental and Moral Science Tutor in the University Correspondence College. I have found their services invaluable, and in particular I feel that the book owes much to the suggestions of Mr. Welton. My brother, Mr. J. F. Stout, has rendered me great assistance in preparing for the press, and has compiled the Index.