(A.) In solid metal work, i. e., metal cast thick enough to resist bending, whether it be hollow or not, violent and various projection may be admitted, which would be offensive in marble; but no sharp edges, because it is difficult to produce them with the hammer. But since the permanence of the material justifies exquisiteness of workmanship, whatever delicate ornamentation can be wrought with rounded surfaces may be advisedly introduced; and since the colour of bronze or any other metal is not so pleasantly representative of flesh as that of marble, a wise sculptor will depend less on flesh contour, and more on picturesque accessories, which, though they would be vulgar if attempted in stone, are rightly entertaining in bronze or silver. Verrochio's statue of Colleone at Venice, Cellini's Perseus at Florence, and Ghiberti's gates at Florence, are models of bronze treatment.
(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 goldsmith's 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 iron-work, formed by alternate cuts on its sides, and the bending down of the several portions. The ordinary domestic window balcony of Verona is formed by mere ribands of iron, bent into curves as studiously refined as those of a Greek vase, and decorated merely by their own terminations in spiral volutes.
Fig. 8.
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.
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 honour 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 colours, and in others blanched into the fairest absence of colour, 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 colour—(therefore to this day the favourite ground of miniature painters). In like manner, the existence of quarries of peach-coloured 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.