Moreover, since the aim of art is to afford pleasure in the intuition of life, the artist will try to reveal the hidden unities that so delight the mind to discover. He will aim to penetrate beneath the surface of experience observed by common perception, to its more obscure logic underneath. In this way he will go beyond what the mere mechanism of imitation requires. The poet, for example, manifests latent emotional harmonies among the most widely sundered things. The subtle novelist shows how single elements of character, apparently isolated acts or trivial incidents, are fateful of consequences. He discloses the minute reactions of one personality upon another. Or he enters into the soul of man himself, into his private and individual selfhood, and uncovers the hidden connections between thought and feeling and impulse. Finally, he may take the wider sweep of society and tradition into view and track out their part in the molding of man and his fate. In the search for unity, the artist is on common ground with the man of science; but with this difference: the artist is concerned with laws operating in concrete, individual things in which he is interested; while the scientist formulates them in the abstract. For the artist, unity is valuable as characterizing a significant individual; for the scientist, it is valuable in itself, and the individual only as an example of it.

This same purpose of affording pleasure in sympathetic vision leads the artist not only to present the unity of life, but so to organize its material that it will be clear to the mind which perceives it. Too great a multitude of elements, elements that are not assorted into groups and tied by relations or principles, cannot be grasped. Hence the artist infuses into the world which he creates a new and wholly subjective simplicity and unity, to which there is no parallel in nature. The composition of elements in a picture does not correspond to any actual arrangement of elements in a landscape, but to the demands of visual perspicuity. The division of a novel into chapters, of the chapters into paragraphs, of the paragraphs into sentences, although it may answer in some measure to the objective divisions of the life-story related, corresponds much more closely to the subjective need for ready apprehension. The artist meets this need halfway in the organization of the material which he presents. Full beauty depends upon an adaptation of the object to the senses, attention, and synthetic functions of the mind. The long, rambling novel of the eighteenth century is a more faithful image of the fullness and diversity of life, but it answers ill to the limited sweep of the mind, its proneness to fatigue, and its craving for wholeness of view.

But even all the reasons so far invoked—the necessity for significance, the interest in unity, the demand for perspicuity—do not, I think, suffice to explain the structure of works of art. For structure has, oftentimes, a direct emotional appeal, which has not yet been taken into account, and which is a leading motive for its presence. Consider, for example, symmetry. A symmetrical disposition of parts is indeed favorable to perspicuity; for it is easier to find on either side what we have already found on the other, the sight of one side preparing us for the sight of the other; and such an arrangement is flattering to our craving for unity, for we rejoice seeing the same pattern expressed in the two parts; yet the experience of symmetry is richer still: it includes an agreeable feeling of balance, steadfastness, stability. This is most evident in the case of visual objects, like a Greek vase, where there is a plain division between right and left similar halves; but it is also felt in music when there is a balance of themes in the earlier and later parts of a composition, and in literature in the well-balanced sentence, paragraph, or poem. To cite the very simplest example, if I read, "on the one hand … on the other hand," I have a feeling of balanced tensions precisely analogous to what I experience when I look at a vase. Structure is not a purely intellectual or perceptive affair; it is also motor and organic, and that means emotional. It is felt with the body as well as understood by the mind. I have used the case of symmetry to bring out this truth, but I might have used other types of unification, each of which has its unique feeling tone, as I shall show presently, after I have analyzed them.

Keeping in mind the motives which explain the structure of works of art, I wish now to distinguish and describe the chief types. There are, I think, three of these, of which each one may include important special forms—unity in variety, dominance, and equilibrium.

Unity in variety was the earliest of the types to be observed and is the most fundamental. It is the organic unity so often referred to in criticism. It involves, in the first place, wholeness or individuality. Every work of art is a definite single thing, distinct and separate from other things, and not divisible into parts which are themselves complete works of art. No part can be taken away without damage to the whole, and when taken out of the whole, the part loses much of its own value. The whole needs all of its parts and they need it; "there they live and move and have their being." The unity is a unity of the variety and the variety is a differentiation of the unity.[Footnote: Cf. Lipps: Aesthetik, Bd. I, Drittes Kapitel.] The variety is of equal importance with the unity, for unity can assert itself and work only through the control of a multiplicity of elements. The analogy between the unity of the work of art and the unity of the organism is still the most accurate and illuminating. For, like the work of art, the body is a self-sufficient and distinctive whole, whose unified life depends upon the functioning of many members, which, for their part, are dead when cut away from it.

The conception of unity in variety as organic represents an ideal or norm for art, which is only imperfectly realized in many works. There are few novels which would be seriously damaged by the omission of whole chapters, and many a rambling essay in good standing would permit pruning without injury, unless indeed we are made to feel that the apparently dispensable material really contributes something of fullness and exuberance, and so is not superfluous, after all. The unity in some forms of art is tighter than in others; in a play closer than in a novel; in a sonnet more compact than in an epic. In extreme examples, like The Thousand and One Nights, the Decameron, the Canterbury Tales, the unity is almost wholly nominal, and the work is really a collection, not a whole. With all admissions, it remains true, however, that offenses against the principle of unity in variety diminish the aesthetic value of a work. These offenses are of two kinds—the inclusion of the genuinely irrelevant, and multiple unity, like double composition in a picture, or ambiguity of style in a building. There may be two or more parallel lines of action in a play or a novel, two or more themes in music, but they must be interwoven and interdependent. Otherwise there occurs the phenomenon aptly called by Lipps "aesthetic rivalry"—each part claims to be the whole and to exclude its neighbor; yet being unable to do this, suffers injury through divided attention.

Unity in variety may exist in any one or more of three modes—the harmony or union of cooperating elements; the balance of contrasting or conflicting elements; the development or evolution of a process towards an end or climax. The first two are predominantly static or spatial; the last, dynamic and temporal. I know of no better way of indicating the characteristic quality of each than by citing examples.

Aesthetic harmony exists whenever some identical quality or form or purpose is embodied in various elements of a whole—sameness in difference. The repetition of the same space-form in architecture, like the round arch and window in the Roman style; the recurrence of the same motive in music; the use of a single hue to color the different objects in a painting, as in a nocturne of Whistler: these are simple illustrations of harmony. An almost equally simple case is gradation or lawful change of quality in space and time—the increase or decrease of loudness in music of saturation or brightness of hue in painting, the gentle change of direction of a curved line. In these cases there is, of course, a dynamic or dramatic effect, if you take the elements in sequence; but when taken simultaneously and together, they are a harmony, not a development. Simplest of all is the harmony between like parts of regular figures, such as squares and circles; or between colors which are neighboring in hue. Harmonious also are characters in a story or play which are united by feelings of love, friendship, or loyalty. Thus there is harmony between Hamlet and Horatio, or between the Cid and his followers.

Aesthetic balance is the unity between elements which, while they oppose or conflict with one another, nevertheless need or supplement each other. Hostile things, enemies at war, business men that compete, persons that hate each other, have as great a need of their opponents, in order that there may be a certain type of life, as friends have, in order that there may be love between them; and in relation to each other they create a whole in the one case as in the other. There is as genuine a unity between contrasting colors and musical themes as there is between colors closely allied in hue or themes simply transposed in key. Contrasting elements are always the extremes of some series, and are unified, despite the contrast, because they supplement each other. Things merely different, no matter how different, cannot contrast, for there must be some underlying whole, to which both belong, in which they are unified. In order that this unity may be felt, it is often necessary to avoid absolute extremes, or at least to mediate between them. Among colors, for example, hues somewhat closer than the complementary are preferred to the latter, or, if the extremes are employed, each one leads up to the other through intermediate hues. The unity of contrasting colors is a balance because, as extremes, they take an equal hold on the attention. The well-known accentuation of contrasting elements does not interfere with the balance, because it is mutual. A balanced unity is also created by contrasts of character, as in Goethe's Tasso, or by a conflict between social classes or parties, as in Hauptmann's Die Weber. Balanced, finally, is the unity between the elements of a painting, right and left, which draw the attention in opposite directions. The third type of unity appears in any process or sequence in which all the elements, one after another, contribute towards the bringing about of some end or result. It is the unity characteristic of all teleologically related facts. The sequence cannot be a mere succession or even a simple causal series, but must also be purposive, because, in order to be aesthetic, the goal which is reached must have value. Causality is an important aspect of this type of unity, as in the drama, but only because a teleological series of actions depends upon a chain of causally related means and ends. The type is of two varieties: in the one, the movement is smooth, each element being harmoniously related to the last; in the other, it is difficult and dramatic, proceeding through the resolution of oppositions among its elements. The movement usually has three stages: an initial phase of introduction and preparation; a second phase of opposition and complication; then a final one, the climax or catastrophe, when the goal is reached; there may also be a fourth,—the working out of the consequences of this last. Illustrations of this mode of unity are: the course of a story or a play from the introduction of the characters and the complication of the plot to the denouement or solving of the problem; the development of a character in a novel from a state of simplicity or innocence through storm and stress into maturity or ruin; the evolution of a sentiment in a sonnet towards its final statement in the last line or two; the melody, in its departure from the keynote, its going forth and return; the career of a line.

As I have indicated before, each type of unity has its specific emotional quality. The very word harmony which we use to denote the first mode is itself connotative of a way of being affected, of being moved emotionally. The mood of this mode is quiet, oneness, peace. We feel as if we were closely and compactly put together. If now, within the aesthetic whole, we emphasize the variety, we begin to lose the mood of peace; tensions arise, until, in the case of contrast and opposition, there is a feeling of conflict and division in the self; yet without loss of unity, because, if the whole is aesthetic, each of the opposing elements demands the other; hence there is balance between them, and this also we not only know to be there, but feel there. The characteristic mood of the evolutionary type of unity is equally unique—either a sense of easy motion, when the process is unobstructed, or excitement and breathlessness, when there is opposition.