But when the seat of the empire was transferred to Constantinople, and Roman art, influenced by Asiatic feeling, and stimulated and elevated by the new faith of Christianity, became transfigured into the solemn splendour of Byzantine art, the architecture of the round arch and the dome and cupola rose to its fullest beauty, and such buildings as St. Sophia at Constantinople, and St. Mark's at Venice, with the churches of Ravenna, mark another great and noble epoch in the arts of design.
Byzantine design, whether in building, in carving, in mosaic, or goldsmiths' work, impresses one with a certain restraint in the midst of its splendour; a certain controlling dignity and reserve appears to be exercised even in the use of the most beautiful materials, as well as in design and the treatment of form.
The mosaics of the Ravenna churches alone are sufficient to exemplify this. The artists seemed fully to realize that the curved surfaces of the dome, the half dome of the apse, or the long flat frieze above the arch columns of the nave of the basilicas, like St. Apollinare in Classe, afforded splendid fields for a splendid material, the cross light from the deep-set windows enriching the effect, and that everything might well be secondary to it. The same principle or feeling is seen in St. Mark's where the architecture is quite simple, the arches and vaulting without mouldings, nothing to interfere with the quiet splendour of the gold or blue fields of mosaic varied with simple typical figures, bold in silhouette, placed frankly upon them, emblems, boldly curving scroll-work, and inscriptions. The execution, too, is as direct and simple as the design. Such design and decoration as this becomes an essential and integral part of the architectural structure and effect.
SKETCH OF PART OF INTERIOR OF DOME, S. MARK'S, VENICE.
MOSAIC OF THE EMPRESS THEODORA, T. VITALE, RAVENNA, SIXTH CENTURY.
Note the way in which the tesseræ are laid (in the head of the Empress Theodora from St. Vitale at Ravenna, for instance). The cube is used as much as possible, but the cubes vary much in size, and are set often with very open joints, the cement lines of the bedding showing quite clearly, and the surface of the work uneven, the tesseræ being worked, of course, from the front and in situ, presenting a varied surface of different facets which, catching the light at different angles, give an extraordinary sparkle and richness to the effect as a whole. In the head of Theodora the effect is enhanced by the discs of mother-of-pearl used for the head-dress.
In the laying of the tesseræ, too, note that the system is followed of defining the outlines with rows of cubes, and building up the masses (as in the nimbus) with concentric rows, as a rule, making the lines of the filling tesseræ follow as far as possible the line of the boundary tesseræ. This, of course, would naturally result as the simplest and most convenient, as well as most expressive, method of laying tesseræ, in defining form by means of small cubes, and is one of the conditions of the work, and when, as in these mosaics, so far from being refined away, or concealed, or any attempt being made (as in later times) to imitate painting, these conditions are boldly and frankly acknowledged, we see how its peculiar beauty, character, and the quality of its ornamental effect depends upon these very conditions.
This principle will be found to hold good and true throughout all art. Directly, from a false idea of refinement, or with the object of displaying mechanical skill, the craftsman is induced to try to conceal the fundamental conditions of his craft, and to make it ape the qualities of some totally different sort of work, he ceases to be an artist, at all events. The true artist in any material is he who in acknowledging its conditions and limitations finds in them sources and opportunities of new beauty, and in being faithful to those conditions makes them subserve his invention.