But, as shown by Layard in his discoveries at Nineveh, a knowledge of colouring was not confined to the Egyptians; it was likewise possessed by the Assyrians. The painted ornaments of the latter are stated to have been remarkably elegant; and although the colours were limited to blue, red, white, yellow, and black, yet they were arranged with so much taste and skill, and the contrasts were so judiciously preserved, that the combinations were in general agreeable to the eye. The pale yellowish-white ground on which the designs were painted, resembled the tint on the walls of Egyptian monuments, and a strong well-defined black outline was found to be as peculiar a feature in Assyrian as in Egyptian painting, black frequently combining with white alone, or alternating with other colours. As far as they have been analysed, the pigments employed were mineral, the brightest being a blue derived from copper. No traces of vegetable colours have been found; it is presumed that they existed, but being subject to more rapid decay than the mineral pigments, they have disappeared. That all the colours, indeed, employed by the ancients were not permanent, was proved by the fact of certain blues and reds, brilliant and vivid when the earth was removed from them, fading rapidly when exposed to the air. From Philocles, the Egyptian, and Gyges, a Lydian, both of whom, according to Pliny, acquired the knowledge of the art of painting in Egypt, the Greeks obtained the knowledge of their _Ars Chromatica_, which they are said to have carried by gradual advances during several centuries, from the monochromatic of their earlier painters, to the perfection of colouring under Zeuxis and Apelles, 450 to 350 B.C. Unfortunately, not long after, or about 300 B.C., art rapidly deteriorated; the invasion of the Romans commenced; and the principles of light, shade, and colours in painting as understood by the Greeks, together with their valuable treatises on the subject were lost. The early Roman and Florentine painters, so eminent in other respects, were almost destitute of those principles, and of truly refined feeling for the effects of colouring. The partial restoration of this branch seems to have been coeval with the earliest practice of painting in oil. The glory of it belongs to the Venetians, to whom the art of painting passed with the last remains of the Greek schools after the capture of Constantinople at the beginning of the thirteenth century. Giovanni Bellini laid the foundation of colouring, and Titian carried it to its highest practical perfection. From the Venetian it extended to the Lombard, Flemish, and Spanish schools. In the practice of these, however, there was perhaps as much of instinct as principle, colouring still remaining to be established in its perfection as a science.