t known, like fragments of the milky sky itself, fallen into the cool
streets, and breaking into the darkened churches. And no work is less
imitable; like Tuscan wine, it loses its savour when moved from its
birthplace, from the crumbling walls where it was first placed. Part of
the charm of this work, its grace and purity and finish of expression,
is common to all the Tuscan sculptors of the fifteenth century; for Luca
was first of all a worker in marble, and his works in earthenware only
transfer to a different material the principles of his sculpture.

These Tuscan sculptors of the fifteenth century worked for the most part
in low relief, giving even to their monumental effigies something of its
depression of surface, getting into them by this means a pathetic
suggestion of the wasting and etherealisation of death. They are haters
of all heaviness and emphasis, of strongly-opposed light and shade, and
seek their means of expression among those last refinements of shadow,
which are almost invisible except in a strong light, and which the
finest pencil can hardly follow. The whole essence of their work is
EXPRESSION, the passing of a smile over the face of a child, the ripple
of the air on a still day over the curtain of a window ajar.

What is the precise value of this system of sculpture, this low relief?
Luca della Robbia, and the other sculptors of the school to which he
belongs, have before them the universal problem of their art; and this
system of low relief is the means by which they meet and overcome the
special limitation of sculpture--a limitation resulting from the
material and the essential conditions of all sculptured work, and which
consists in the tendency of this work to a hard realism, a one-sided
presentment of mere form, that solid material frame which only motion
can relieve, a thing of heavy shadows, and an individuality of
expression pushed to caricature. Against this tendency to the hard
presentment of mere form trying vainly to compete with the reality of
nature itself, all noble sculpture constantly struggles: each great
system of sculpture resisting it in its own way, etherealising,
spiritualising, relieving its hardness, its heaviness and death. The use
of colour in sculpture is but an unskilful contrivance to effect, by
borrowing from another art, what the nobler sculpture effects by
strictly appropriate means. To get not colour, but the equivalent of
colour; to secure the expression and th