(a) Among the different materials in which sculptors have executed images of gods, wood is one of the most ancient. A trunk, a post at the top of which a head can be indicated, such was the beginning. Among the earliest examples of the temple image many are of wood, but the material was also used even in the days of Pheidias. The colossal Minerva of Pheidias at Plataea was mainly carved from wood which was gilded, the head, hands, and feet being of marble[189]; Myron, too[190], executed a Hecate out of wood here with only one head and body, and no doubt for Aegina, where Hecate was most revered and a festival took place annually in her honour, a festival which the Aeginetans maintained the Thracian Orpheus had inaugurated for them.
Generally speaking, wood, when it is not covered over with gilding or some other precious material, by reason of its texture and the grain of it, appears too fine a material for works of importance and more appropriate to smaller figures, for which purpose it was frequently used in the Middle Ages, and is still thus utilized nowadays.
(b) Other materials of most importance are ivory, associated with gold, founded bronze and marble.
(α) As is well known, Pheidias employed ivory and gold for his masterpieces, such as his Olympian Zeus, and also for his famous colossal Athene in the Acropolis of Athens, who carried on her hand an image of Victory, itself being larger than life-size. The nude portions of the body were made out of sheets of ivory, the drapery and mantle from gold plates, which could be removed. This type of workmanship in yellowish ivory and gold dates from a period in which statues were coloured, a kind of representation which steadily approximated to the one colour tone of bronze and marble. Ivory is an extremely pure material, smooth and without the granular character of marble, and, moreover, costly. And among the Athenians the costliness of the statues of their gods was itself of importance. The Pallas at Plataea had merely a superficial gilding, that at Athens solid metal plates. The statues had to be both of colossal size and of the richest material. Quatremère de Quincy has written a masterly work upon these works, upon the "toreutic" of the ancients. "Toreutic"—τορεύειν, τόρευμα—is primarily applicable to figures whose lines are brought out by engraving in metal, or cutting of some kind such as cut stones; one uses the expression, however, to indicate entire works or parts of entire works in metal, which are executed by means of moulds and the founder's art, that is, not by means of engraving, then, still more remotely from the original meaning, of superb figures on earthenware utensils, and finally in the widest sense of mouldings[191] on bronze. Quatremère's researches have particularly been directed to the technical aspect of the execution; he calculates what must have been the size of the plates made of elephants' tusks, and, among other things, how much space, in proportion to the gigantic dimensions of the figure, they would leave covered. From another point of view he is equally concerned to reproduce for us from the sketches, or other evidence[192] we possess from antiquity, a drawing of the seated figure of Zeus, and, most of all, the great chair with its rich decorations of bas-reliefs, and by so doing to give us in every respect some conception of the splendour and perfection of the work.
In the Middle Ages ivory is mainly used for smaller works of very varied character, such as Christ on the Cross and the Virgin Mary, or yet again for drinking vessels with scenes of hunting and the like, in which cases ivory, on account of its smoothness and hardness, is in many respects preferable to wood.
(β) The material which was most favoured and most widely employed by the ancients was bronze, in the casting of which it attained a success of the highest mastery. Preeminently during the period of Myron and Polycletus it was the prevailing material utilized in statues of deities and other kinds of sculpture. The darker, less defined colour, the sheen, the smoothness of bronze generally, has not reached the abstract formality of the white marble, and it is at the same time warmed. The bronze which the ancients used was partly gold and silver, partly copper, varying considerably in the degrees of its component parts. The so-called bronze of Corinth is, for example, a composition unique of its kind which originated after the burning of Corinth from the almost incredible wealth of this city in statues and vessels of bronze. Mummius had many statues carried off on his ships; and the excellent man was so full of anxiety for their safe deliverance in Rome that he informed the captain that in case of loss he must recreate the same exactly or suffer, such was the threat, heavy punishment. In the founding of bronze the ancients attained an incredible mastery, by aid of which it was possible to them to cast it securely despite its extreme thinness. It is possible to regard such a feat as merely a matter of technical dexterity which is unconnected with true art. Every artist, however, works upon a certain material, and it is an essential quality of genius to be complete master of the same. Dexterity and adaptability in matters which concern the technique and instruments of its work constitute one distinct aspect of genius. On account of this virtuosity in the founder's art a work of sculpture in this medium involved a less expensive process, and was in the reach of a larger number than the chiselling out of marble statues. A second advantage, which the ancients were able to attain in casting their work in bronze, was the purity thereby acquired, which they carried so far that their bronze statues did not require further enchasening, and consequently lost nothing of the finer marks of expression, which is almost inevitable where such a process is necessary. If we consider, then, the extraordinary number of works of art, which originated in this facility and mastery over technical matters, we cannot fail to be astonished and admit that the artistic sense for sculpture is a distinctive impulse and instinct of spirit, which can only, that is, in so overwhelming a degree, appear in one period and one people. In the whole of the Prussian State, for example, at the present time we can easily reckon up the number of bronze statues, the single bronze door of a church we find in Gnesen, and, with the exception of the standing figures of Blücher at Berlin and Breslau, and Luther at Wittenburg, we have merely a few more in Königsberg and Düsseldorf[193].
The very various tone and the infinite adaptability to form and fusibility of this material, which may accommodate itself to every kind of representation, gives to sculpture the pass into every conceivable variety of production, and makes its sensitive material suitable for a host of conceits, prettinesses, utensils, ornaments, and innocent trifles of all kinds. Marble, on the other hand, is limited in its suitability for the depicting of objects and their size; it is, for instance, possible to execute bas-reliefs in it of a certain size on urns and vases. It is, however, unsuitable for smaller objects. In the case of bronze, however, which is not merely cast into specific forms, but can also be beaten into shape and informed by the engraver's tools, there is hardly any type or size of representation which it does not command. We may here, by way of more definite example, instance the case of coinage minting. In this art, too, we find that the ancients executed masterworks of beauty, albeit in the technical aspect of the mere mintage[194] they stand as yet far behind our present elaboration of all that is mechanical in the design. The coins in fact were not really minted, but beaten but of pieces of metal closely resembling a globular form. This department of the art attained its culmination in the time of Alexander. The coins of the Roman Empire have already deteriorated. In our own time Napoleon endeavoured to revive the beauty of antique work in his medals and coinage, and they are of great excellence. In other states, however, the mere worth of the metal and accurate weight is mainly important in the mintage of coin.
(γ) The last kind of material exceptionally favourable to sculpture is stone, which possesses independently the external aspect of consistency and permanence. The Egyptians long before chiselled out their sculptured colossi with a labour that spared no pains from the hardest granite, syenite and basalt. Marble is, however, most directly, as a material, in harmony with the aims of sculpture through its soft purity, whiteness, no less than by the absence of definite colour and the mildness of its sheen, and in particular possesses, by virtue of its granular texture and the soft interfusion of light which it carries, a great advantage over the chalk-like dead whiteness of gypsum, which is too bright, and easily kills with its glare the finer shadows. We find a distinct preference given to marble, only at a later epoch of the Greek school, that is during the period of Praxiteles and Scopas, who executed their most famous works in marble. Pheidias no doubt worked in marble, but for the most part only in the execution of head, hands, and feet. Myron and Polycletus mainly made use of bronze. Praxiteles and Scopas, on the other hand, appear to have sought to remove from sculpture that feature which is alien to its main principle, namely colour. No doubt it is undeniable that the beauty of the ideal of sculpture is capable of being embodied in bronze as in marble, with no diminution whatever of its purity. When, however, as was the case with Praxiteles and Scopas, art begins to approach the softer forms of grace and charm of figure, the marble asserts itself as the more congenial medium. For marble "encourages, by virtue of the transparency of its surface, a softness of outline, its gentle articulation[195] and mild conjunction; add to this that the tender and artificial elaboration of consummate work always appears more clearly on the soft whiteness of stone than on bronze, however noble it may be, which, in proportion as the transition of green is beautifully gradated, makes the lustres and the reflections all the more disturbing to the effect of repose[196]." For the same reason the careful attention, which at this period was paid to effects of light and shade, whose nuances and gradations are more clearly marked by marble than by bronze, was a further reason why stone should be preferred to metal.
(c) In conclusion we ought to associate with the above more important kinds of material precious stones and glass.
The ancient gems, cameos and pastes are invaluable. They repeat in fact on the smallest scale, yet with consummate finish, the entire survey of sculpture, from the simple figure of a god, through all the varied forms of grouping to every possible kind of conceit in dainty delight and prettiness. Winckelmann, however, observes with regard to the Stosch collection[197]: "It was while looking at this that I was made aware of a truth, which afterwards became to me of great value in elucidating monuments, very difficult to understand; and the truth is this, that on cut stones, no less than on imposing works of sculpture, we very rarely come across events which took place after the Trojan war, or after the return of Odysseus to Ithaca, if we only except the one case of the Heracleidae and the descendants of Hercules; for in this latter case the limits of history and fable still overlap, and fable is the main subject of these artists. Only one example of the tale of the Heracleidae, however, is known to me personally." As for gems, the genuine and most consummately executed figures are of the greatest beauty, fine as the work of organic Nature, and may be inspected through a magnifying glass without any loss to the purity of their delineation. I refer to this fact in proof that the technique of art in such cases is almost an art of intuition; the fineness is such that the artist is unable as the sculptor is to follow the work with his eyes, but is rather compelled to feel after it. He holds the stone which is made fast on wax against tiny sharp wheels which are made to spin by means of a flying-wheel, and in this way cuts out the forms. By this process what we have is a kind of instinctive sense, which takes in and directs so consummately the conception, the intention of line and drawing, that we can almost fancy ourselves to have before us in these stones, when one sees them properly illuminated, a relief work.