“Sex and Character” is undoubtedly one of those rare books that will be studied long after its own times, and whose influence will not pass away, but will penetrate deeper and deeper, compelling amazement and inviting reflection in steadily expanding circles. It may be noted with satisfaction that the book is by no means in harmony with contemporary thought. The discussions, so much in favour nowadays, concerning the emancipation of women, sexuality, the relation of women to culture, and so forth, are deprived of their data by this publication; for here, laid down with all the penetrating acumen of the trained logician, is a characterisation of sexual types, “M” (the ideal man), and “W” (the ideal woman), which traces all the much discussed psychological phenomena back to a final source, and actually gives a definitive solution to the feminine problem, a solution altogether alien to the field of inquiry wherein the answer has hitherto been sought. In the science of characterology, here formulated for the first time, we have a strenuous scientific achievement of the first importance. All former psychologies have been the psychology of the male, written by men, and more or less consciously applicable only to man as distinguished from humanity. “Woman does not betray her secret,” said Kant, and this has been true till now. But now she has revealed it--by the voice of a man. The things women say about themselves have been suggested by men; they repeat the discoveries, more or less real, which men have made about them. By a highly original method of analysis, a man has succeeded for the first time in giving scientific and abstract utterance to that which only some few great artists have suggested by concrete images hitherto. Weininger, working out an original system of characterology (psychological typology) rich in prospective possibilities, undertook the construction of a universal psychology of woman which penetrates to the nethermost depths, and is based not only on a vast systematic mastery of scientific knowledge, but on what can only be described as an appalling comprehension of the feminine soul in its most secret recesses. This newly created method embraces the whole domain of human consciousness; research must be carried out on the lines laid down by Nature--in three stages, and from three distinct points of view: the biologico-physiological, the psychologically descriptive, and the philosophically appreciative. I will not dwell here on the equipment essential for such a task, the necessary combination of a comprehensive knowledge of natural history with a minute and exhaustive mastery of psychological and philosophical science--a combination destined, perhaps, to prove unique.