Principles of design
Between mosaic and painting, the art with which it has most in common, there has been a reciprocal influence of varying intensity. In colour and style the earliest known Greek figurative mosaics with representational motifs, which date from the end of the 5th century bce, resemble contemporary vase painting, especially in their outline drawing and use of very dark backgrounds. The mosaics of the 4th century tended to copy the style of wall paintings, as is seen in the introduction of a strip of ground below the figures, of shading, and of other manifestations of a preoccupation with pictorial space. In late Hellenistic times there evolved a type of mosaic whose colour gradations and delicate shading techniques suggest an attempt at exact reproduction of qualities typical of the art of painting.
In Roman imperial times, however, an important change occurred when mosaic gradually developed its own aesthetic laws. Still basically a medium used for floors, its new rules of composition were governed by a conception of perspective and choice of viewpoint different from those of wall decoration. Equally important was a simplification of form brought about by the demand for more expeditious production methods. In the same period, the increasing use of more strongly coloured materials also stimulated the growing autonomy of mosaic from painting. As a means of covering walls and vaults, mosaic finally realized its full potentialities for striking and suggestive distance effects, which surpass those of painting.
The general trend towards stylization—that is, reduction to two-dimensionality—in late antique Roman painting (3rd and 4th centuries ce) may have been stimulated by experimentation with colour in mosaic and particularly by the elimination of many middle tones for the sake of greater brilliance. The central role played at that time by mosaic in church decoration, for which it is particularly well suited, encourages the assumption that the roles had shifted and painting had come under its influence. The strong, sinuous outlines and the absence of shading that came to characterize painting during certain periods of Byzantine and western European art of the Middle Ages may have originated in mosaic technique and use of materials. It is notable, however, that from the Renaissance to the 20th century mosaic was again wholly dependent on painting and its particular forms of illusionism.
In modern mosaic practice, the main tendency is to build on the unique and inimitable qualities of the medium. Although not a few of the works created in the 20th century reveal the influence of painting, figurative or abstract, the art came a long way toward self-realization. By and large the modern mosaic makers share with their medieval predecessors the conviction that there are functions to which the materials of mosaic lend themselves with particular appropriateness.