What will happen when civilised society thoroughly grasps what heredity means? There are signs, of which Mr Archdall Reid's book is only one, that that time may not be very far off. It is a mere accident that recognition of the plain facts has been delayed so long. Were the physiology of inheritance slightly less complex, its paramount importance would long ago have been evident to all, and man would have perceived that this is the point at which he can really shape his own destiny. The steady application of a breeding law would accomplish more in three generations than all the criminal and sanitary enactments that the centuries have devised. Mr Galton has been proclaiming this truth to a sceptical world for forty years. Nature, to use his antithesis, is much; nurture incomparably little. Circumstances have lately combined to bring these matters into prominence. Physical deterioration, the alarming increase in the relative numbers of the insane, the utility of teaching the minds of starving children, the relation of the State to the unemployed, and all questions of grave national anxiety—they are problems of national physiology, and as physiological problems they are at last beginning to be studied.

Political economists have hitherto incurred no reproach if their doctrine were not based on physiological evidence. That is not their department; and though illustrative references to such topics are considered becoming in their writings, neither economist nor politician has been expected to go to physiology for his fundamental facts.