Although we are a part of the growth of impersonal forms of life we seldom know anything about it until it is well in the past. We do not know when—for obscure reasons that even the psychologist can hardly detect—we use one word rather than another, or use an old word in a new sense, that we are participating in the growth of the language organism. And yet this organism is vast, complex, logical, a marvel, apparently, of constructive ingenuity. It is the same with tradition and custom. We never tell a story or repeat an act precisely as we heard or saw it; everything is unconsciously modified by passing through us and the social medium of which we are a part, and these modifications build logical structures which human intelligence, in the course of time, may or may not discover. The students of folk-lore and primitive culture deal chiefly with such material. The working or vitality of one element of a tradition over another consists in some power to stimulate impulses in the human mind, which is, therefore, a selective agent in the process, but we are no more aware of what is going on, usually, than we are of the selective action of our digestive organs. The folkways and _mores_ which Professor Sumner has so amply discussed are almost wholly of this nature. The commercialism of our time offers a modern instance. Nobody, I suppose, has intended it: it has come upon us through the mechanical inventions, the opening of new countries and other conditions which have stimulated industry and commerce, these in turn imposing themselves upon the minds and habits of men at the expense of other interests. An epoch, like an individual, has its somewhat special functions, and a mind somewhat subdued to what it works in. Such a development as that of the Italian painting of the Renaissance, or of a particular school, like the Venetian, is a real organism, fascinating to study in the interactions and sequences of its activity, waxing and waning under the spur of immediate influences without thought of the living whole which history now discovers.