and species as best work in with, are most rhythmical to, their surroundings--natural selection sees to that. III. In art the place of natural selection is taken by man's selection; and all forms of art which man keeps and does not send into limbo, all art which man finds suitable to his wants, rhythmical with his habits, must have that same quality of interdependence of parts, of interchange of function. Only in the case of art, the organic necessity refers not to outer surroundings, but to man's feeling; in fact, man's emotion constitutes necessity towards art, as surrounding nature constitutes necessity for natural objects. Now man requires organic harmony, that is, congruity and co-ordination of processes, because his existence, the existence of every cell of him, depends upon it, is one complete microcosm of interchange, of give-and-take, diastole-systole, of rhythm and harmony; and therefore all such things as give him impressions of the reverse thereof, go against him, and in a greater or lesser degree, threaten, disturb, paralyse, in a way poison or maim him. Hence he is for ever seeking such congruity, such harmony; and his artistic creativeness is conditioned by the desire for it, nay, is perhaps mainly seeking to obtain it. Whenever he spontaneously and truly creates artistic forms, he obeys the imperious vital instinct for congruity; nay, he seeks to eke out the insufficient harmony between himself and the things which he _cannot_ command, the insufficient harmony between the uncontrollable parts of himself, by a harmony created on purpose in the things which he _can_ control. To a large extent man feels himself tortured by discordant impressions coming from the world outside and the world inside him; and he seeks comfort and medicine in harmonious impressions of his own making, in his own strange inward-outward world of art. This, I think, is the true explanation of that much-disputed-over _ideal_, which, according to definitions, is perpetually being enthroned and dethroned as the ultimate aim of all art: the ideal, the imperatively clamoured-for mysterious something, is neither conformity to an abstract idea, nor conformity to actual reality, nor conformity to the typical, nor conformity to the individual; it is, I take it, simply conformity to man's requirements, to man's inborn and peremptory demand for greater harmony, for more perfect co-ordination and congruity in his feelings.