Nor was multi-colourisation confined to the Greek sculptors. It was a natural development in the art of carving in every country, arising, as we have seen, out of the desire of the artist to bring his work into a closer relation with life. The Egyptians and the Chaldeans never limited themselves to the use of form in their statues and in their architecture, but sought for ways of rendering colour. The great Asiatic races used enamel as the basis of their decoration. Here we find the origin of the multi-coloured sculpture of Babylon, Assyria, and Susa, and, at a later date, that of Medea and Persia. This art reached Byzantium--a country which gained the highest skill in glass mosaic--and also Rome. Persian artists, following in the train of the conquering Arabs, brought the secrets and methods of their art to many European countries, and among them to Spain and Portugal. The influence spread also from Byzantium, and, in a lesser degree, from Rome, and soon multi-colourisation was universally adopted, and all statues, whether of wood, stone, or copper, were covered with colour. Centuries passed before a reaction set in. It became a creed of artistic faith that the use of colour to accentuate works in relief was barbarous. The reason of the change is very simple. Many of the ancient coloured statues had lost their colour by lapse of time, and those who saw them were deceived, believing that as they were then, so they had been created. Then pictures came to be painted more frequently, and colour was allowed to them, while form alone was accorded to statuary. But the tradition of polychrome statuary yet persisted, and at the opening of the Renaissance still fought for life. Italy possessed some great statue colourists in the fifteenth century. We know of coloured statues and bas-reliefs by Donatello, by Mino of Fiesole, by Pisáno of Luca, by della Robbia, and others. Even much later we find examples of the continued use of colour. Such, for instance, are the equestrian statues of the ducal family of Sabbroneta and the groups in the chapels of the Sacromonte at Varullo. It is important to remember that the great masters deplored the abandonment of statue colouring, and, among others, Michael Angelo wrote an instructive and precious letter upon the subject. Coloured statuary was more persistent in the south than in the north. Flanders, Germany, and afterwards France were converted from the custom. Yet Jan van Eyck collaborated with the sculptor, as did also André Beaunevau. The life-size statues which decorate the Château of Madrid built for Francis I., and those in the Toulouse Museum, taken from the Basilica of St. Sermin, prove that coloured statuary still persisted in the sixteenth century. These last figures are of special interest from their analogy with Spanish polychrome statuary.