WE have seen that beauty springs from unity in diversity, and that unity results from processes of comparison wherein like is placed with like - like lines, or shapes, or colors, or significances - until the multiplicity of individual units is related to a few types, and of these types one becomes dominant. Yet, though this conforms to the law of its being, the mind, like a child at play, quickly tires of the same old types. It will return to them; it must know all the time that they are there; but for the moment its interest can be retained only by showing it something different.

Contrast, as an artistic principle, is the result of this necessity. It is a means of giving zest to decorative compositions which, however harmonious, would without it be insipid. It opposes curved lines to straight, plain surfaces to ornamented, light tones to dark, and warm colors to cold, and by this opposition gives the charm of vividness to each.

In this, of course, artistic practice merely conforms to the general law of life, since all our states, both physical and emotional, are intensified by contrast. Sunshine always seems more brilliant after shadow, tranquillity more grateful after excitement. It is indeed only through contrast that we can discriminate between one state or emotion and another. We can enjoy warmth only because we have known cold, and rest because we have known effort. We perceive form or outline only where there is a contrast of hue or tone. We know smooth textures through contrast with rough, and warm colors through contrast with cold; while lines, shapes and colors are set off and their peculiar qualities made more marked through contrast with their op-posites.

It happens, therefore, that in the effort so to select and arrange the furnishings of a given room as to make the room beautiful, the esthetic problem of the decorator is twofold. He must first of all ensure an easily perceptible unity through principality and the repetition of like elements, and he must also invest his room with a quality of interest and decorative charm through the opposition of contrasting elements. The contrasts chiefly employed will be those of hue, in which hues more or less markedly unlike are used together; of tone, in which relatively light tones are opposed to relatively dark; of purity, in which relatively pure colors are opposed to relatively neutral; of textures; of lines; of shapes; and of ornamented surfaces as opposed to plain.

Besides its esthetic importance, contrast appears in decoration as a physical factor, the operation of which is to make unlike elements seem more unlike. It is in the nature of our perceptive faculties that when unlike things are compared their unlikeness is accentuated. When we see a tall chair and a low chair in the same group the tall one appears to be taller than it really is, and the short one still shorter by contrast. A picture hung in the midst of a large wall space seems smaller than it would if hung in a small space; a long room appears longer if it is also narrow; a round mirror on a rectangular wall space is more striking than a rectangular mirror would be; pale colors appear more pale against darker grounds; hues more intense against their complementaries; and a richly figured drapery fabric gains in emphasis and distinction from being hung against a plain wall fabric. Figures 18 and 19, taken from Lipp's Raumaesthetik und geornetrisch-optische Tauschnngen, illustrate this physical effect of contrast. In the first figure the first and second lines are of equal length, as are the third and fourth, and the fifth and sixth; yet the second appears to be distinctly shorter than the first, and the fourth distinctly shorter than the third. In the second figure the two mean circles are of the same diameter, but through contrast with the two extremes the second is made to appear smaller than the third.

Figure 18.

Figure 19.

Like phenomena appear constantly in decoration. Whenever the treatment of a room is so arranged that the eye makes a comparison of similar lines of different lengths, or of similar shapes of different sizes, their apparent differences are increased by the contrast. Dining chairs placed against a vertically paneled wall appear lower and more squat by reason of the contrast between the lines of their backs and those of the paneling; small tables look even smaller in a big room, as do small rugs on a large floor space; a bookcase, highboy, chest of drawers or piano will appear wider in a narrow space, narrower in a wide space; taller in a room with a low ceiling, and shorter in a room with a high ceiling.

For the same reason, whenever one dimension of a room or of any object is emphasized, the other dimensions are apparently diminished. A narrow bookcase, cabinet or chair appears to be taller than a wide piece of the same actual height, as a couch without a back seems to be longer than a high-backed settee of the same actual length. The practical importance of these considerations, which will be developed at length in the chapter on Proportion, lies in the fact that beauty and fitness in decoration are so largely dependent upon the apparent - as opposed to the actual - relationships in size and shape among the elements of a composition; and inasmuch as contrast is sure to change the apparent relationships in some degree the decorator must be prepared to foresee and allow for these changes.

Colors, even more than shapes, are affected by contrast. Color practice is in fact immensely complicated by the fact that a color is never seen by itself, but always in relation to other colors. These other colors react upon it, altering in some degree its appearance both in hue and in tone. Chevreul set forth the general principle involved in the formula: When the eye sees at the same time two contiguous colors, they will appear as dissimilar as possible, both in optical composition and in height of tone.