b. When metal is beaten thin, it becomes what is technically called 'plate,' (the flattened thing,) and may be treated advisably in two ways: one, by beating it out into bosses, the other by cutting it into strips and ramifications. The vast schools of goldsmiths' work and of iron decoration, founded on these two principles, have had the most powerful influences over general taste in all ages and countries. One of the simplest and most interesting elementary examples of the treatment of flat metal by cutting is the common branched iron bar, Fig. 8, used to close small apertures in countries possessing any good primitive style of ironwork, formed by alternate cuts on its sides, and the bending down of the severed portions. The ordinary domestic window balcony of Verona is formed by mere ribbons of iron, bent into curves as studiously refined as those of a Greek vase, and decorated merely by their own terminations in spiral volutes.
All cast work in metal, unfinished by hand, is inadmissible in any school of living art, since it cannot possess the perfection of form due to a permanent substance; and the continual sight of it is destructive of the faculty of taste: but metal stamped with precision, as in coins, is to sculpture what engraving is to painting.
158. Thirdly. Stone-sculpture divides itself into three schools: one in very hard material; one in very soft; and one in that of centrally useful consistence.
Fig. 8.
a. The virtue of work in hard material is the expression of form in shallow relief, or in broad contours: deep cutting in hard material is inadmissible; and the art, at once pompous and trivial, of gem engraving, has been in the last degree destructive of the honor and service of sculpture.
b. The virtue of work in soft material is deep cutting, with studiously graceful disposition of the masses of light and shade. The greater number of flamboyant churches of France are cut out of an adhesive chalk; and the fantasy of their latest decoration was, in great part, induced by the facility of obtaining contrast of black space, undercut, with white tracery easily left in sweeping and interwoven rods—the lavish use of wood in domestic architecture materially increasing the habit of delight in branched complexity of line. These points, however, I must reserve for illustration in my Lectures on Architecture. To-day, I shall limit myself to the illustration of elementary sculptural structure in the best material,—that is to say, in crystalline marble, neither soft enough to encourage the caprice of the workman, nor hard enough to resist his will.
159. c. By the true 'Providence' of Nature, the rock which is thus submissive has been in some places stained with the fairest colors, and in others blanched into the fairest absence of color that can be found to give harmony to inlaying, or dignity to form. The possession by the Greeks of their λευκος λιθος was indeed the first circumstance regulating the development of their art; it enabled them at once to express their passion for light by executing the faces, hands, and feet of their dark wooden statues in white marble, so that what we look upon only with pleasure for fineness of texture was to them an imitation of the luminous body of the deity shining from behind its dark robes; and ivory afterwards is employed in their best statues for its yet more soft and flesh-like brightness, receptive also of the most delicate color—(therefore to this day the favorite ground of miniature painters). In like manner, the existence of quarries of peach-colored marble within twelve miles of Verona, and of white marble and green serpentine between Pisa and Genoa, defined the manner both of sculpture and architecture for all the Gothic buildings of Italy. No subtlety of education could have formed a high school of art without these materials.
160. Next to the color, the fineness of substance which will take a perfectly sharp edge, is essential; and this not merely to admit fine delineation in the sculpture itself, but to secure a delightful precision in placing the blocks of which it is composed. For the possession of too fine marble, as far as regards the work itself, is a temptation instead of an advantage to an inferior sculptor; and the abuse of the facility of undercutting, especially of undercutting so as to leave profiles defined by an edge against shadow, is one of the chief causes of decline of style in such incrusted bas-reliefs as those of the Certosa of Pavia and its contemporary monuments. But no undue temptation ever exists as to the fineness of block fitting; nothing contributes to give so pure and healthy a tone to sculpture as the attention of the builder to the jointing of his stones; and his having both the power to make them fit so perfectly as not to admit of the slightest portion of cement showing externally, and the skill to insure, if needful, and to suggest always, their stability in cementless construction. Plate X. represents a piece of entirely fine Lombardic building, the central portion of the arch in the Duomo in Verona, which corresponds to that of the porch of San Zenone, represented in Plate I. In both these pieces of building, the only line that traces the architrave round the arch, is that of the masonry joint; yet this line is drawn with extremest subtlety, with intention of delighting the eye by its relation of varied curvature to the arch itself; and it is just as much considered as the finest pen-line of a Raphael drawing. Every joint of the stone is used, in like manner, as a thin black line, which the slightest sign of cement would spoil like a blot. And so proud is the builder of his fine jointing, and so fearless of any distortion or strain spoiling the adjustment afterwards, that in one place he runs his joint quite gratuitously through a bas-relief, and gives the keystone its only sign of preëminence by the minute inlaying of the head of the Lamb into the stone of the course above.
161. Proceeding from this fine jointing to fine draughtsmanship, you have, in the very outset and earliest stage of sculpture, your flat stone surface given you as a sheet of white paper, on which you are required to produce the utmost effect you can with the simplest means, cutting away as little of the stone as may be, to save both time and trouble; and above all, leaving the block itself, when shaped, as solid as you can, that its surface may better resist weather, and the carved parts be as much protected as possible by the masses left around them.