"The mosaics of SS. Cosmo and Damian (A.D. 526--530) are the finest of ancient Christian Rome. Above the arch appear, on each side of the Lamb, four angels, of excellent but somewhat severe style; then follow various apocalyptic emblems: a modern walling up having left but few traces of the four and twenty elders. A gold surface, dimmed by age, with little purple clouds, forms the background: though in Rome, at least, at both an earlier and later date, a blue ground prevailed. In the apsis itself, upon a dark blue ground, with golden-edged clouds, is seen the colossal figure of Christ; the right hand raised, either in benediction or teaching, the left holding a written scroll; above is the hand, which is the emblem of the First Person of the Trinity. Below, on each side, the apostles Peter and Paul are leading SS. Cosmo and Damiano, each with crowns on their heads, towards the Saviour, followed by St. Theodore on the right, and by Pope Felix IV., the founder of the church, on the left. This latter, unfortunately, is an entirely restored figure. Two palm-trees, sparkling with gold, above one of which appears the emblem of eternity, the phœnix--with a star-shaped nimbus, close the composition on each side. Further below, indicated by water-plants, sparkling also with gold, is the river Jordan. The figure of Christ may be regarded as one of the most marvellous specimens of the art of the middle ages. Countenance, attitude, and drapery combine to give him an expression of quiet majesty, which, for many centuries after, is not found again in equal beauty and freedom. The drapery, especially, is disposed in noble folds, and only in its somewhat too ornate details is a further departure from the antique observable. The saints are not as yet arranged in stiff parallel forms, but are advancing forward, so that their figures appear somewhat distorted, while we already remark something constrained and inanimate in their step. The apostles Peter and Paul wear the usual ideal costume. SS. Cosmo and Damiano are attired in the late Roman dress: violet mantles, in gold stuff, with red embroideries of oriental barbaric effect. Otherwise the chief motives of the drapery are of great beauty, though somewhat too abundant in folds. The high lights are brought out by gold and other sparkling materials, producing a gorgeous play of colour which relieves the figures vigorously from the dark blue background. Altogether, a feeling for colour is here displayed, of which no later mosaics with gold grounds give any idea. The heads, with the exception of the principal figure, are animated and individual, though without any particular depth of expression; somewhat elderly, also, in physiognomy, but still far removed from any Byzantine stiffness; St.