It will be said at once that all these concrete representations necessarily fail to realize the artist's thought, and are inadequate, inferior in exactness, to scientific and philosophic knowledge; in a measure this is true, and would be important if the method of art were demonstrative, instead of being, as has been said, experimental and inductive. So, too, all thinkers, using the actual world in their processes, are at a disadvantage. The figures of the geometer, the quantities of the chemist, the measurements of the astronomer, are inexact approximations to their equivalent in the mind. Art, as an embodiment in mortal images, is subject to the conditions of mortality. Hence arises its human history, the narrative of its rise, climax, and decline in successive ages. The course of art is known; it has been run many times; it is a simple matter. At first art is archaic, the sensible form being rudely controlled by the artist's hand; it becomes, in the second stage, classical, the form being adequate to the thought, a transparent expression; last, it is decadent, the form being more than the thought, dwarfing it by usurping attention on its own account. The peculiar temptation of technique is always to elaboration of detail; technique is at first a hope, it becomes a power, it ends in being a caprice; and always as it goes on it loses sight of the general in its rendering, and dwells with a near eye on the specific. Nor is this attention to detail confined to the manner; the hand of the artist draws the mind after it, and it is no longer the great types of manhood, the important fates of life, the primary emotions in their normal course, that are in the foreground of thought, but the individual is more and more, the sensational in plot, the sentimental in feeling. This tendency to detail, which is the hallmark of realism, constitutes decline. It arises partly from the exhaustion of general ideas, from the search for novelty of subject and sensation, from the special phenomena of a decaying society; but, however manifold may be the causes, the fact of decline consists in the lessened scope of the matter and the increased importance of the form, both resulting in luxuriant detail. Ideas as they lose generality gain in intensity, but in the history of art this has not proved a compensation. In Greece the three stages are clearly marked both in matter and manner, in Aeschylus, Sophocles, and Euripides; in England less clearly in Marlowe, Shakspere, and Webster. How monstrous in the latter did tragedy necessarily become! yet more repulsive in his tenderer companion-spirit, Ford. In Greek sculpture, passing into convulsed and muscular forms or forms of relaxed voluptuousness, in Italian painting, in the romantic poetry of this century with us, the same stages are manifest. Age parallels age. Tennyson in artistic technique is Virgilian, we are aware of the style; but both Virgil and Tennyson remain classic in matter, in universality, and the elemental in man. Browning in substance is Euripidean, being individualistic, psychologic, problematic, with special pleading; classicism had departed from him, and left not even the style behind. The great opposition lies in the subject of interest. Is it to know ourselves in others? Then art which is widely interpretative of the common nature of man results. Is it to know others as different from ourselves? Then art which is specially interpretative of abnormal individuals in extraordinary environments results. This is the opposition between realism and idealism, while both remain in the limits of art, as these terms are commonly used. It belongs to realism to tend to the concrete of narrow application, but with fulness of special trait or detail. It belongs to idealism to tend to the concrete of broad application, but without peculiarity. The trivial on the one hand, the criminal on the other, in the individual, are the extremes of realistic art, while idealism rises to an almost superhuman emphasis on that wisdom and virtue, and the beauty clothing them, which are the goal of a nation's effort. Race-ideas, or generalizations of a compact and homogeneous people summing up their serious interpretations of life, their moral choices, their aspiration and hope in the lines of effort that seem to them highest, are the necessary matter of idealism; when these are expressed they are the Greek spirit, the Roman genius, great types of humanity on the impersonal, the national scale.