The ideas that form the starting point for the launching of a course of instruction in any branch of knowledge are necessarily merely provisional for the understanding of its scope and are not intended to be its perfect and adequate presentation. Imperfect though they are, these notions easily justify their presence by furnishing matter for contrast: to know what a thing is not is a step toward an understanding of what it is. Reflection and cool discrimination are not slow to intrude themselves, so much the more imperiously as the mind is more cultivated. But through their intervention they break the first charm, and then the enjoyment of the art gives place to criticism. To classify the problems that will be brought into view in a philosophy of art, no better procedure can be found, it seems to us, than to adopt the plan drawn up by Aristotle, which responds to the most rigorous didactic demands.