The masterpiece among the mosaics is clearly the labors of Hercules cycle in the _triclinium_ (46). These were part of a standard repertory, available for copying from a book of cartoons (we have seen this sort of thing in Pompeii), but here the artist has stamped his own personality on the hackneyed scenes. In his hands they are at once learnedly allusive and bloodily violent. Thus the Augean stables, which Hercules cleaned by diverting a river to run through them, are simply suggested by a river and a pitchfork. Violence is often rather hinted at than insisted on, as in the slit-like eye of the dying Nemean lion, or the Picasso-like protruding eye of the terrified horse of Diomedes (Fig. 13.6). Sometimes the effect is gained by a topical touch, as when Geryon, the triple-headed giant, is given a suit of scaly armor, like the barbarians (cataphractarii) on Trajan’s column. But the full baroque excess, as insistent as in the frieze from the Pergamene altar, or the Laocoön group, comes out in the scene in the east lobe where five huge giants, foreshortened with a technique which anticipates Michelangelo’s on the ceiling of the Sistine Chapel, convulsively, despairingly, imploringly, yet full of impotent rage, turn their deep-sunk eyes to heaven as they strive to pull from their flesh Hercules’ deadly arrows, steeped in the blood of the Centaur Nessus. In the north lobe the apotheosis of Hercules is no doubt the mosaicist’s enforced tribute to his Imperial master, but in the scenes of metamorphosis in the entrance-ways to the apses--Daphne into a laurel, Cyparissus into a cypress, Ambrosia into a vine--he is following his own paradoxical bent, accepting as it were the challenge of expressing so dynamic a thing as the change from one form to another in the obdurate medium of mosaic.