Roman Book-illustration—See ILLUMINATED MANUSCRIPTS. This was a highly-developed branch of art in Rome, as appears from the description of Varro's 15 books of Imagines, illustrated with 700 pictures, and from the passage in Martial already referred to. The extant material, however, is mostly later than the period we are concerned with. But the famous illustrations to a 4th cen tury codex of the Iliad, in the Ambrosiana at Milan, reflect, ac cording to Wickhoff, the Romano-Pompeian style, while the illus trations of the Vatican Virgil, No. 3,235, seem to be 4th century copies of pictures of Augustan date. On the other hand, the pic tures in the 4th century Virgil (Vat. 3,867), notably the "Assem bly of the Gods," are in the contemporary "frontal" style here illustrated by the Junius Bassus panel in opus sectile (Plate IV., fig. I I). Roman influence inspires the celebrated Dioscorides of Vienna of the year 512, the style of which is closely akin to that of the Vienna Genesis, and is still vital in the loth century in the Joshua rotulus of the Vatican, many of whose pictures clearly depend upon Roman historic relief.
The gaps in the available knowledge of Roman painting can be filled up to a certain extent by what we learn from the remains of the sister art of mosaic, which, being less easily destroyed, have survived in thousands to the present day (see Mosmc). The Roman artists were, generally speaking, alive to the essential dif ferences of principle between the arts, and did not seek to produce the impression of painting, executed with a liquid medium, by the use of solid materials. Amongst the mosaics of Roman date which employ a large number of exceedingly minute cubes, an illusion akin to that of painting seems, it is true, to be the aim, though even here the Roman mosaicist never entirely transcends the limits imposed by his material. The most conspicuous examples of this more naturalistic manner are the pavement in the Lateran mu seum signed by the Greek Heraclitus, which appears to reproduce the "unswept hall" of Sosos of Pergamum (see Mosmc), and the mosaic of the doves from Hadrian's villa, preserved in the Capi toline museum, inspired by the "Drinking Dove" of the same artist. The former of these contains about I 20, the latter as many as 16o cubes to the square inch.
A distinction must be drawn between opus tessellaturn, consist ing of cubes regularly disposed in geometrical patterns, and opus vermiculaturn in which a picture is produced by means of cubes irregularly placed. The two methods were commonly used in con junction by the Romans, who recognized that a pavement should emphasize the f orm of the room to which it belonged by means of a geometrical border, while figure-subjects should be reserved for the central space. The celebrated pavement at Palestrina
(Plate IV., fig. 7), with an extensive view of the Nile and its sur roundings, is possibly the earliest known Roman picture in mosaic. Though it can scarcely be dated to Sulla's restoration of the Prae nestine temple, it cannot be later than the second half of the 1st century, and seems early Augustan both in its Egyptianizing sub ject and in its landscape motives. Small mosaic-pictures isolated in geometrical pavements were called emblemata, and were often transported from the great centres of production to distant prov inces, where pavements were prepared for their reception. The subjects of these emblemata, like those of the wall-paintings of Pompeii, were taken frequently from Greek mythology, and it is not easy to determine what degree of originality is to be assigned to Roman artists. We note a certain interest in the great figures of literature and philosophy. A subject commonly known as "The Academy of Plato" shows us a group of Greek philosophers en gaged in discussion. In provincial pavements it is not uncommon to find portraits of poets or philosophers used to fill ornamental schemes of decoration, as in the famous mosaic at Trier signed by Monnus. The portrait mosaic of Virgil, mentioned on p. 401 discovered in a villa at Sousse in Tunisia (ancient Hadrume tum) shows a marked new interest in Roman literature, while it has also been shown that the mythological scenes depicted by the mosaic-workers of the later imperial period are frequently inspired, not by Greek poetry or even Greek artistic tradition, but by the works of Ovid ; and the popularity of the legend of Cupid and Psyche is, doubtless, to be traced to its literary treat ment by Apuleius. Besides a well-chosen repertory of geomet rical patterns, the mosaic-workers make use of vegetable motives taken from the vine, the olive, the acanthus or the ivy, as well as traditional figures, such as the seasons, the winds, the months and allegorical figures of all kinds, forming elements in a scheme of decoration which, though often of great richness, is never lacking in symmetry and sobriety. Mosaic pavements were a common luxury in the provinces, those of Gaul and of Roman Africa being specially celebrated; and there are fine examples from both Africa and Roman Britain in the British Museum.