Far from confining himself within the narrow limits of one branch of his profession, Vernet determined to take as wide a range as possible. At Rome, he made the acquaintance of Lucatelli, Pannini, and Solimene. Like them, he studied the splendid ruins of the architecture of ancient Rome, and the noble landscapes of its environs, together with every interesting scene and object, especially the celebrated cascades of Tivoli. He paid particular attention to the proportions and attitudes of his figures, which were mostly those of fishermen and lazzaroni, as well as to the picturesque appearance of their costume. Such love of nature and of art, such assiduous study of nature at different hours of the day, of the phenomena of light, and such profound study of the numerous accessories essential to beauty and effect, made an excellent landscape painter of Vernet, though his fame rests chiefly on the unrivalled excellence of his marine subjects. Diderot remarks, that "though he was undoubtedly inferior to Claude Lorraine in producing bold and luminous effects, he was quite equal to that great painter in rendering the effects of vapor, and superior to him in the invention of scenes, in designing figures, and in the variety of his incidents." At a later period, Diderot compared his favorite painter to the Jupiter of Lucian, who, tired of listening to the lamentable cries of mankind, rose from table and exclaimed: 'Let it hail in Thrace!' and the trees were immediately stripped of their leaves, the heaviest cut to pieces, and the thatch of the houses scattered before the wind: then he said, "Let the plague fall on Asia!" and the doors of the houses were immediately closed, the streets were deserted, and men shunned one another; and again he exclaimed: 'Let a volcano appear here!' and the earth immediately shook, the buildings were thrown down, the animals were terrified, and the inhabitants fled into the surrounding country; and on his crying out: 'Let this place be visited with a death!' the old husbandman died of want at his door. Jupiter calls that governing the world, but he was wrong. Vernet calls it painting pictures, and he is right.