In India also the elaborate caste systems, although due in part to conquest, seem also to have come about by the hardening of occupation-classes. The priests, powerful because of their supposed intercourse with superhuman powers, taught their mystic traditions to their children and so built up a hereditary corporation, known, finally, as the Brahman caste. The military caste was apparently formed in a similar manner, while in industry “veneration for parental example and the need of an exact transmission of methods”[110] rendered all employments hereditary. In fact, says one writer, the caste system was in its origin “simply an instinctive effort for the organization of labor.”[111] In the case of so intricate a caste society as that of India much may also be ascribed to the reaction of the theory upon the system. When the idea that caste is natural had become prevalent and sanctified, it tended to create caste where it would not otherwise have existed. A settled state of society is favorable, and change hostile, to the growth of caste, because it is necessary that functions should be continuous through several generations before the principle of inheritance can become fixed. Whatever breaks up existing customs and traditions tends to abolish hereditary privilege and throw men into a rough struggle, out of which strong, coarse natures emerge as victors, to found, perhaps, a new aristocracy. Thus the conquest of southern Europe by northern tribes led to a period of somewhat confused readjustment, in which men of natural power bettered their status. The classes which emerged were as much the result of competition as derived by inheritance from those of tribal society. And so the openness of classes in our own day _may_ be due as much to confusion as to a permanent decline in the caste principle. That a low state of communication and of enlightenment are favorable to caste, while intelligence—especially political intelligence—and facility of intercourse antagonize it, becomes evident when we consider what, psychologically speaking, caste is. It is an organization of the social mind on a biological principle. That functions should follow the line of descent instead of adjusting themselves to individual capacity and preference, evidently means the subordination of reason to convenience, of freedom to order. The ideal principle is not biological but moral, based, that is, on the spiritual gifts of individuals without regard to descent. Caste, then, is something which, we may assume, will give way to this higher principle whenever the conditions are such as to permit the latter to work successfully; and this will be the case when the population is so mobilized by free training and institutions that just and orderly selection is practicable.