The world may improve in art as in other things. Yet, as every thinker knows, all improvements are in the nature of developments that are made in strict accordance with fixed laws. We have found that scientific classification, as well as artistic construction, demands that like be put with like. This demand is beyond the reach of any human power that may seek to change it. It exists in the constitution of the mind. No architect can disregard it, and produce a building satisfactory to men in general. No building has ever obtained and preserved a reputation as a work of art, in which this requirement has been neglected.
The true reason, therefore, for not introducing the forms of Greek, Romanesque, and Gothic architecture into the same building, is that, as a rule, such a course is fatal to unity of effect. These principal styles and some of the subordinate styles developed from them differ so essentially that to blend them is to cause confusion in the form where the mind demands intelligibility, which, so far as our present line of thought is applicable, means something in which many repetitions of similar appearances reveal that all are parts of the same whole. Buildings in which there are very few, if any, forms alike, are not, whatever else they may be, works of art.The Genesis of Art-Form, XII.
So far as the appearance of forms alone is concerned, there is no reason why certain features of the Greek style should not accompany certain of the Gothic. To use them together would not violate in the least the fundamental principle of art, that like forms should be put together. At the same time, to do so would cause art to associate features that have come to be clearly dissociated in the mind. For this reason, it is possible that, as long as the world lasts, no artist can mix them extensively without suggesting to some an amount of incongruity wholly inconsistent with those effects of unity invariably present in arts of the highest character.Idem, Ix.
Under all the arts are certain principles that successful products need to exemplify. As applied to building, for instance, it is not because the Gothic artist did not mix horizontal with arched coverings for windows that it should not be done to-day. Our artists should be actuated by a higher motive than imitation. What they should avoid is a violation of the principle exemplified by the Gothic builders, which principle is to put, wherever it is possible, like with like. It was pointed out in Chapter XVII of “The Genesis of Art-Form ” that in strict accordance with this principle, as it is applied in all the other arts, there might be a legitimate style in which, from the lower storey up, the acuteness of the arches in each storey would be gradually increased; also, that in these days of easy and extensive methods of transportation, there might be a legitimate style, in which, through the use of stones or of other materials of different hues, the effects of contrast in coloring could be produced, even on exteriors.Painting, Sculpture, and Architecture as Representative Arts, XXI.
The use of color enters largely into effects in painting, and much imitation of natural forms characterizes both painting and sculpture. Neither fact is true of architecture. Its effects are often confined to those of forms alone. This makes these of supreme importance. Its forms, moreover, are originated by the artist. This makes it easy to have them such as interfere with what may be called the natural requirements of art. For both reasons, the architect needs to be exceedingly careful in his work. A painter has but to copy a tree as he sees it in nature, and every part of it will be consonant. The leaves or branches will differ in size and shape and, in the autumn, at least, differ sufficiently in color to suggest differences in combination and material. But, comparing leaf with leaf and branch with branch, the same principle of formation will so manifest itself in every part of the tree that no one who sees it can doubt that each belongs to the same organism. A building should appear to be as much a unity in this sense as a tree. Exact repetition of the same forms, as already explained, would always make it seem thus. But, in architecture, exact repetition is not always possible; nor even, if we wish to produce thoroughly natural effects, desirable. The method that is both possible and desirable is consonance. A moment’s reflection will reveal, too, that there are certain very simple devices of arrangement which necessarily secure this effect. It ought to reveal, also, that the effect is important enough to make even a child notice the defects in cases in which it is neglected.The Genesis of Art-Form, XV.