ABSTRACT
The ability possessed by any individual in any mental trait is the result of (I) his original nature, (2) the extent to which his original tendencies have matured by mere inner growth, and (3) the circumstances of his life and training. His original nature is determined partly by sex, partly by his remote ancestry or race, partly by his near ancestry or family, and partly by the unknown causes of variation whereby children of the same parents receive differing inheritances. Vvehave then to study the influence of sex, remote ancestry, near ancestry, maturity and enuironment,
By way of preface to an account of sex differences it is well to note that their existence does not necessarily imply in any case the advisability of differences in school and home training, and, on the other hand, that even if the mental make-up of the sexes were identical it might still be wisest to educate them differently. It is true that a difference of two groups in a mental trait will theoretically involve differences in treatment, but practical considerations apart from that of developing the highest efficiency in that trait may outweigh the advantages of the differential treatment. For instance, consumptives theor-
etically need a different mode of life from people with healthy lungs, but it might in some cases be wiser to leave a consumptive to his ordinary habits rather than to cause in him consciousness of his disease and worry concerning it. On the other hand, two boys might be identical in mental structure, yet their education might best be very different if we wished to make one of them a chemist and the other a psychologist.
