But Grosse wishes us to complete the collection of historical evidence with ethnographical and prehistoric materials, for we cannot obtain really general laws of art from the exclusive study of cultivated peoples, "just as a theory of reproduction exclusively based upon the form it takes with mammifers, must necessarily be imperfect!" He is, however, aware that the results of experiences among savages and prehistoric races do not alone suffice to furnish us with an equipment for such investigations as that concerning the nature of Art, and, like any ordinary mortal, he feels obliged to interrogate, before starting, the spirit of man. He therefore proceeds to define Aesthetic on apriorist principles, which, he remarks, can be discarded when we shall have obtained the complete theory, in like manner with the scaffolding that has served for the erection of a house. Words! Words! Vain words! He proceeds to define Aesthetic as the activity which in its development and result has the immediate value of feeling, and is, therefore, an end in itself. Art is the opposite of practice; the activity of games stands intermediate between the two, having also its end in its own activity. The Aesthetics of Taine and of Grosse have been called sociological. Seeing that any true definition of sociology as a science is impossible, for it is composed of psychological elements, which are for ever varying, we do not delay to criticize the futile attempts at definition, but pass at once to the objective results attained by the sociologists. This superstition, like the naturalistic, takes various forms in practical life. We have, for instance, Proudhon (1875), who would hark back to Platonic Aesthetic, class the aesthetic activity among the merely sensual, and command the arts to further the cause of virtue, on pain of judicial proceedings in case of contumacy.