Such were the walls of Pompeii. Let us now glance at the pavements. They will astonish us much more. At the outset the pavements were quite plain. There was a cement formed of a kind of mortar; this was then thoroughly dusted with pulverized brick, and the whole converted into a composition, which, when it had hardened, was like red granite. Many rooms and courts at Pompeii are paved with this composition which was called _opus signinum_. Then, in this crust, they at first ranged small cubes of marble, of glass, of calcareous stone, of colored enamel, forming squares or stripes, then others complicating the lines or varying the colors, and others again tracing regular designs, meandering lines, and arabesques, until the divided pebbles at length completely covered the reddish basis, and thus they finally became mosaics, those carpetings of stone which soon rose to the importance and value of great works of art. The house of the Faun at Pompeii, which is the most richly paved of all, was a museum of mosaics. There was one before the door, upon the sidewalk, inscribed with the ancient salutation, _Salve!_ Another, at the end of the prothyrum, artistically represented masks. Others again, in the wings of the atrium, made up a little menagerie,--a brace of ducks, dead birds, shell-work, fish, doves taking pearls from a casket, and a cat devouring a quail--a perfect masterpiece of living movement and precision. Pliny mentions a house, the flooring of which represented the fragments of a meal: it was called _the ill-swept house_. But let us not quit the house of the Faun, where the mosaic-workers had, besides what we have told, wrought on the pavement of the œcus a superb lion foreshortened--much worn away, indeed, but marvellous for vigor and boldness. In the triclinium another mosaic represented Acratus, the Bacchic genius, astride of a panther; lastly the piece in the exædra, the finest that exists, is counted among the most precious specimens of ancient art. It is the famous battle of Arbelles or of Issus. A squadron of Greeks, already victorious, is rushing upon the Persians; Alexander is galloping at the head of his cavalry. He has lost his helmet in the heat of the charge, his horses' manes stand erect, and his long spear has pierced the leader of the enemy. The Persians, overthrown and routed, are turning to flee; those who immediately surround Darius, the vanquished king, think of nothing but their own safety; but Darius is totally forgetful of himself. His hand extended toward his dying general, he turns his back to the flying rabble and seems to invite death. The whole scene--the headlong rush of the one army, the utter confusion of the other, the chariot of the King wheeling to the front, the rage, the terror, the pity expressed, and all this profoundly felt and clearly rendered--strikes the beholder at first glance and engraves itself upon his memory, leaving there the imperishable impression that masterpieces in art can alone produce.