These were the artists who formed the second school of art, and established its end and limits. On it was founded the third period of style, in which refinement induced a grace and beauty not to be surpassed. The masters of this period were--Appelles, Protogenes, Aristides, Euphranor, Pausius, and the pupils of Pamphilius, and his master Eupompus. The last named artist was of Sicyon; and his authority was so great, that out of the Asiatic and Grecian chords of painting he formed a third, by dividing the last into the attic and Sicyonian. Pliny says that, when consulted by Zysippus on a standard of imitation in art, he pointed to the crowd passing by--observing that nature, not an artist, should be the object of imitation. Pamphilius, a Macedonian, the master of Appelles, adopted the doctrines of Eupompus. To the art of painting, he joined the study of mathematics, and held, that, without the aid of geometry, no artist could arrive at any perfection. In Appelles, we are told by Pliny, unrivalled excellence was found. Grace was his powerful and peculiar faculty, in which he surpassed all his predecessors. His Venus Anadyomene, which was long after purchased by Augustus for one hundred talents, or £20,000 sterling, was esteemed the most faultless creation of the Grecian pencil, the most perfect example of that simple yet unapproachable grace of expression, of symmetry of form, and exquisite finish, in which may be summed up the distinctive beauties of his genius. Hotogenes was next to him in merit. The most celebrated of his works was his figure of Jalysus, with his dog, which occupied him seven years. Aristides, of Theles, and cotemporary of Appelles, was the first, who, by the rules of art, obtained a perfect knowledge of expressing the passions and affections of the mind. In one figure, he expressed the anguish of maternal affection, and the pangs of death. Euphranor, the Isthmian, and pupil of Aristides, is said to have carried this refinement of expression still further. Skilled in Sculpture, as well as in Painting, his conceptions were noble and elevated; his style masculine and bold; and he was the first who distinguished himself, by imparting majesty to his heroes.