ins bathe as it were in a perpetual sunset. The air is constantly
flooded with a radiance which seems to transfuse itself through every
part of the city, making all its ruinous and hoary age bright and
living, forming pictures and harmonies indescribable of the humblest
objects.

The white marbles hitherto described were principally for exterior
use. But as Roman wealth and luxury increased coloured marbles were
employed for internal decoration; and the effects which the Greeks
obtained by the application of pigments, the Romans obtained by the
rich hues of precious marbles incrusting their buildings, and durable
as these buildings themselves. At first these rare materials were used
with a degree of moderation, chiefly in the form of mosaics of small
discs or cubes for the pavements of halls and courts. But at length
massive pillars were constructed of them, and the vast inside brick
surfaces of imperial baths and palaces were crusted over and concealed
by slabs of rare and splendid marbles, the lines of which had no
necessary connection with the mass behind or beneath. Carthage from
the spoils of its temples supplied Rome with many of its rarest
columns; and it is probable that not a few of these survive in the
Christian basilicas that occupy the sites and were built out of the
materials of the old Pagan structures. With the decay of the Roman
Empire the use of coloured marbles in art increased, so that even
busts and statues had their faces and necks cut in white and the
drapery in coloured marble. It attained its fullest development in the
Byzantine style, of which, as it appeals to the senses more by colour
than by form, it is a predominant characteristic, necessary to its
vitality and expression. The early Christian builders contemplated
this mode of decoration for their interiors only. Very rarely had they
the means to apply it to the outside surface, as in St. Mark's in
Venice, which is the great type of the Byzantine church, coloured
within and without with the rich hues of marbles and mosaics. Our
great Gothic cathedrals, as an eminent architect has said, were the
creation of one thought, and hence they were complete when the workmen
of the architects left them, and their whole effect is dominated by
one idea or one set of ideas; but the early Roman churches were the
results of a general co-operation of associated art, and the large and
plain surfaces of the interiors were regarded by the sculptor as a
framewo