Failure to know the facts concerning the distribution of mental traits, the organization of intellect, and the laws of heredity and variation, leads to much wasted effort on the part of all who deal by profession with people. The most frequent error is that of demanding that others adopt one’s own religious beliefs, standard of living, reaction time, or politics—usually with the idea that they will be greatly benefited thereby. Another common error of theory is that general happiness would be increased if some force could be established great enough to hold all down to the same plane of work, leisure, and reward. In education it has been assumed that justice would be well served by prescribing the same curriculum, at the same rate, at the same time, for every child. If the uniformity of thought and action, to which these theories and practices tend, could be secured, the result would be deadening. Such uniformity cannot, however, be achieved, because of the biological forces of heredity and variation. The formulæ governing the interplay of these forces are little known, and they therefore lie outside of human control. Many thinkers believe that nothing would be lost and much be gained for human welfare, by cutting off the variants who fall low in intellect and stability, and by increasing the number of those who fall highest, on the curve of distribution. However, it is possible to take, and perhaps to defend, the view that this would be meddlesome rather than helpful. Civilization becomes complex through the discoveries and inventions of superior deviates. It was they who invented wheel and lever, clock and calendar, court and statute book. They discovered the use of electricity, gravity, and steam. When moral life and industrial life become very complicated, great numbers of men are unable to meet the situations devised, and perish mentally, morally, and physically. Law may become so intricate that only the steadiest can suffer its restrictions. Mechanical and chemical contrivances may grow so numerous and complex that typical human nature cannot cope with them. Would it be better, then, to end invention at its source, by eliminating superior deviates? Or would mankind thereby lose other gifts, wholly benign for all, which only the superior deviate can bestow? In the absence of the highly endowed, would there not be a return to barbarism? And, if so, would the greatest good of the greatest number be thus promoted? Or should the welfare of the majority give way as a social ideal to the welfare of the best—the most capable, the most upright, the most enduring? Is it possible to evolve a social order in which the greatest good of all can be well served, since biological inequalities are so very great? These are questions for social and educational philosophy.