By the application of mathematical methods to statistics we can ascertain their real meaning, if they have any. If, as frequently happens, they have none, mathematical analysis is worse than useless. Mr. Galton is the pioneer of this study, which Professor Karl Pearson has named biometrics. Biometrics is not eugenics, as some have supposed, but is a branch of scientific enquiry which, like genetics, obstetrics and many more, contributes to the foundations of eugenics. In the Appendix reference is made to various publications, mostly inexpensive, which deal with biometrics. In the text I have availed myself of biometric, genetic and other results impartially. Differences of opinion between this school and that of scientific workers are to be regretted by the eugenist; but it is for him to accept and use knowledge of eugenic significance no matter by what method it has been obtained. Directly he fails to do so he ceases to be a eugenist and becomes the ordinary partisan. No reference is made in the following pages, for instance, to the _law of ancestral inheritance_, formulated by the Master to whom the volume is dedicated and of whom all eugenists are the followers. I believe that law, despite its beauty, to be without basis in fact and incompatible with demonstrated Mendelian phenomena: and though the book is dedicated to Mr. Galton, it is more deeply dedicated to the Future. This, indeed, is the _Credo_ of the eugenist: _Expecto resurrectionem mortuorum, et vitam venturi saeculi._ * * * * * Woman is Nature's supreme instrument of the future. The eugenist is therefore deeply concerned with her education, her psychology, the conditions which permit her to exercise her great natural function of choosing the fathers of the future, the age at which she should marry, and the compatibility between the discharge of her incomparable function of motherhood and the lesser functions which some women now assume. Obstetrics, and the modern physiology and psychology of sex, must thus be harnessed to the service of eugenics, and I hope to employ them for the elucidation, in a future volume, of the problems of woman and womanhood, thus regarded. CONTENTS PART I THE THEORY OF EUGENICS