150. Thus, his truest respect for the law of the entire creation is shown by his making the most of what he can get most easily; and there is no virtue of art, nor application of common sense, more sacredly necessary than this respect to the beauty of natural substance, and the ease of local use; neither are there any other precepts of construction so vital as these—that you show all the strength of your material, tempt none of its weaknesses, and do with it only what can be simply and permanently done.
151. Thus, all good building will be with rocks, or pebbles, or burnt clay, but with no artificial compound; all good painting, with common oils and pigments on common canvas, paper, plaster, or wood,—admitting, sometimes for precious work, precious things, but all applied in a simple and visible way. The highest imitative art should not, indeed, at first sight, call attention to the means of it; but even that, at length, should do so distinctly, and provoke the observer to take pleasure in seeing how completely the workman is master of the particular material he has used, and how beautiful and desirable a substance it was, for work of that kind. In oil painting its unctious quality is to be delighted in; in fresco, its chalky quality; in glass, its transparency; in wood, its grain; in marble, its softness; in porphyry, its hardness; in iron, its toughness. In a flint country, one should feel the delightfulness of having flints to pick up, and fasten together into rugged walls. In a marble country one should be always more and more astonished at the exquisite colour and structure of marble; in a slate country one should feel as if every rock cleft itself only for the sake of being built with conveniently.
Plate X.—Marble Masonry in the Duomo of Verona.
152. Now, for sculpture, there are, briefly, two materials—Clay, and Stone; for glass is only a clay that gets clear and brittle as it cools, and metal a clay that gets opaque and tough as it cools. Indeed, the true use of gold in this world is only as a very pretty and very ductile clay, which you can spread as flat as you like, spin as fine as you like, and which will neither crack, nor tarnish.
All the arts of sculpture in clay may be summed up under the word "Plastic," and all of those in stone, under the word "Glyptic."
153. Sculpture in clay will accordingly include all cast brick-work, pottery, and tile-work[128]—a somewhat important branch of human skill. Next to the potter's work, you have all the arts in porcelain, glass, enamel, and metal; everything, that is to say, playful and familiar in design, much of what is most felicitously inventive, and, in bronze or gold, most precious and permanent.
154. Sculpture in stone, whether granite, gem, or marble, while we accurately use the general term "glyptic" for it, may be thought of with, perhaps, the most clear force under the English word "engraving." For, from the mere angular incision which the Greek consecrated in the triglyphs of his greatest order of architecture, grow forth all the arts of bas-relief, and methods of localized groups of sculpture connected with each other and with architecture: as, in another direction, the arts of engraving and wood-cutting themselves.
155. Over all this vast field of human skill the laws which I have enunciated to you rule with inevitable authority, embracing the greatest, and consenting to the humblest, exertion; strong to repress the ambition of nations, if fantastic and vain, but gentle to approve the efforts of children, made in accordance with the visible intention of the Maker of all flesh, and the Giver of all Intelligence. These laws, therefore, I now repeat, and beg of you to observe them as irrefragable.