building, so as to be still dependent
on the shadow of its background and direction of protective
line.

176. Let me recommend you at once to take what pains may be needful to
enable you to distinguish these four kinds of sculpture, for the
distinctions between them are not founded on mere differences in
gradation of depth. They are truly four species, or orders, of
sculpture, separated from each other by determined characters. I have
used, you may have noted, hitherto in my Lectures, the word 'bas-relief'
almost indiscriminately for all, because the degree of lowness or
highness of relief is not the question, but the _method_ of relief.
Observe again, therefore--

[Illustration: XII.

BRANCH OF PHILLYREA.]

A. If a portion of the surface is absolutely flat, you have the first
order--Flat Relief.

B. If every portion of the surface is rounded, but none undercut, you
have Round Relief--essentially that of seals and coins.

C. If any part of the edges be undercut, but the general protection of
solid form reduced, you have what I think you may conveniently call
Foliate Relief,--the parts of the design overlapping each other, in
places, like edges of leaves.

D. If the undercutting is bold and deep, and the projection of solid
form unreduced, you have Full Relief.

Learn these four names at once by heart:--

Flat Relief.
Round Relief.
Foliate Relief.
Full Relief.

And whenever you look at any piece of sculpture, determine first to
which of these classes it belongs; and then consider how the sculptor
has treated it with reference to the necessary structure--that
reference, remember, being partly to the mechanical conditions of the
material, partly to the means of light and shade at his command.

[Illustration: FIG. 9.]

177. To take a single instance. You know, for these many years, I have
been telling our architects, with all the force of voice I had in me,
that they could design nothing until they could carve natural forms
rightly. Many imagined that work was easy; but judge for yourselves
whether it be or not. In Plate XII., I have drawn, with approximate
accuracy, a cluster of Phillyrea leaves as they grow, Now, if we wanted
to cut them in bas-relief, the first thing we should have to consider
would be the position of their outline on the marble;--here it is, as
far down as the spring of the leaves. But do you suppose that is what an
ordinary sculptor could either lay for his