All the white marbles which I have thus described were used in Rome principally for external architecture; and beautiful as a city largely built of them may have looked, it must have had, nevertheless, a garishness and artificiality which would offend the artistic eye.  When newly constructed, the Roman temples in the time of the emperors must have been oppressive, reflecting the hot sunshine from their snowy cellae and pillared porticoes with an insufferable glare.  Marble—­unlike sandstones, clay-slates, and basalts, which are kindred to the earth and the elements, and find themselves at home in any situation, all things making friends with them, mosses, lichens, ivies—­is a dead, cold material, and does not harmonise with surrounding circumstances.  Like the snow, which hides the familiar brown soil from us, with its unearthly and uncongenial whiteness, its perpetual snow chills and repels human sympathies.  Nature, for a similar reason, introduces white flowers very sparingly into the landscape; and their dazzling whiteness is toned down by the greenery around them, and the balancing of coloured objects near at hand, so that they do not in reality attract more notice than other flowers.  The ancient Greeks themselves, keenly sensitive as they were to all external influences, had a fine instinct for this want of harmony between white marble and the tones of nature and the feelings of man; and therefore, in many instances, they coloured not only the marble buildings exposed to view outside, but even the marble statues carefully secluded in the niches within.  The Parthenon was thus tinted with vermilion, blue, and gold, which seems to us, who now see only the golden hue with which the suns of ages have dyed its pure Pentelic marble, a barbarous superfluity, but which, to the people of the time, was necessary on account of the dazzling brightness of its material, concealing the exquisite beauty of the workmanship, and the finished grace of its proportions.  Colour was used with perfect taste to relieve the sculptured details of the exterior, to articulate and ornament mouldings, and to harmonise the pure white temple with the dark blue sky of Greece and the rich warm tones of her landscape.  The magnificent sarcophagi of white marble recently discovered at Sidon, belonging to the best type of Greek art, are most effectively adorned with different tints and gradations of red and purple, gold being sparingly applied.  We see many traces of bright colouring on the columns and other parts of the buildings in the Roman Forum.  The bas-reliefs on the Lumachella marble of Trajan’s Column were originally picked out with profuse gilding and vivid colours; the egg and arrow moulding of the capital being tinted green, red and yellow, the abacus blue and red, the spirals yellow, the prominent figures gilt against backgrounds of different hues, and the water of the various rivers blue.  Statues of the deities in Rome were nearly all coloured; and they received a fresh coat of vermilion—­which, although it was the hue of divinity, was extremely fugacious—­on anniversary occasions or in times of great national rejoicing.