insignia, differing from the sculpture
destined for other purposes. Hence they are obviously mistaken who
count certain tablets as diptychs which have no ascription to any
consul, but represent the Muses, Bacchantes, or Gods. These seem
to me to have been book covers." Probably the selected form of an
upright tablet for the majority of ivory carvings is based on
economic principles: the best use of the most surface from any
square block of material is to cut it in thin slices. In their
architecture the southern mediaeval builders so treated stone, building
a substructure of brick and laying a slab or veneer of the more
costly material on its surface: with ivory this same principle
was followed, and the shape of the tusk, being long and narrow,
naturally determined the form of the resulting tablets.

The Throne of Ivan III. in Moscow and that of St. Peter in Rome
are also magnificent monuments of this art. Ivory caskets were the
chief manifestation of taste in that medium, during the period of
transition from the eighth century until the revival of Byzantine
skill in the tenth century. This form of sculpture was at its best
at a time when stone sculpture was on the decline.

There is a fascinating book cover in Ravenna which is a good example
of sixth century work of various kinds. In the centre, Christ is
seen, enthroned under a kind of palmetto canopy; above him, on
a long panel, are two flying angels displaying a cross set in a
wreath; at either end stand little squat figures, with balls and
crosses in their hands. Scenes from the miracles of Our Lord occupy
the two side panels, which are subdivided so that there are four
scenes in all; they are so quaint as to be really grotesque, but
have a certain blunt charm which is enhanced by the creamy lumpiness
of the material in which they are rendered. The healing of the
blind, raising of the dead, and the command to the man by the pool
to take up his bed and walk, are accurately represented; the bed
in this instance is a form of couch with a wooden frame and
mattress, the carrying of which would necessitate an unusual amount
of strength on the part of even a strong, well man. One of the most
naive of these panels of the miracles is the curing of "one
possessed:" the boy is tied with cords by the wrists and ankles,
while, at the touch of the Master, a little demon is seen issuing
from the top of the head of the sufferer, waving its arms proudly
to celebrate its freedom!