Quite apart from the more physical investigations, where statistical methods yield more concrete and definite results, he has utilized direct experimentation where that has been possible, has cited the larger records of history, of literature, and of the more technical portions of psychology and biology. It must forever remain true that advance in this field of comparative psychology must make use of arguments by analogy, of parallelisms, assisted by direct reinforcement of evidence from the investigations of animal life, from the study of the abnormal, from the lessons of history. Method here is not a matter of theoretical preference, but of judgment; and the ability that can turn method into account, not subordinating the chief end to its requirements nor distorting method to strengthen favorite conclusions, is the equipment which the investigator in this field must possess to an unusual degree. Appreciating the difficulties of this undertaking, students of psychology and education, unless they believe that Dr. Hall is fundamentally following a false clue, have reason to be deeply grateful for so much of this work as constitutes an encyclopedia of adolescence. They have the privilege, which many will doubtless exercise, of discrediting this or that group of data; but they can hardly help recognizing that the general perspective of importance and bearing based upon the material thus made available, has on the whole been ably reproduced.
The chapters that best represent this encyclopedic feature are those that deal (the first two) with the varied and detailed factors of physical changes of growth; the fourth, which deals with the disorders of immaturity; the ninth, that treats of changes in the sense endowment and in the voice; and again the later chapters, recounting from a more historical point of view the recognition of adolescence in custom (Chapter XIII.), in religion (Chapter XIV.), in society (Chapter XV.), together with the racial problem of adolescence, which must be treated both theoretically and practically whenever higher races come in contact with lower ones (Chapter XVIII.). A second group of chapters takes up more specifically those questions that are central to adolescence, and in which the element of sex predominates. Chapters VI. and VII. consider the more physiological portions of this problem; Chapter XL is devoted to adolescent love; while Chapter XVII. contains a résumé of the entire topic of the feminine side of adolescence in psychology and education. A third group of chapters includes those in which the philosophic basis is uppermost and which together constitutes in some measure a statement of the author's philosophical and psychological point of view. Chapter X., on evolution and the feelings and instincts characteristic of normal adolescence; Chapter XVI.; on intellectual development and education; Chapter VIII., which considers adolescence in literature, biography and history, represent the more distinctively philosophical contributions; while Chapter III., on the development of the motor powers, represents the