es are carved, so that you may put your finger in at one
hole and see it at the bottom of another. The only end all this extra
labor seems to have attained is that of changefulness in the shadows of
the holes between the leaves, in which one sees dark rims with light at
the bottom, a condition which certainly adds a mysterious lightness to
the whole mass. It is a very refined and appropriate use of
undercutting, but would only be possible where time could be spent to
secure a variant of such epicurean delicacy, as all the superfluous wood
must be taken out through the spaces between the leaves, and in this
case they are not overlarge for that purpose.

Work which has its background entirely cut away, and which is afterward
glued or "planted" on a fresh background to save labor, can not be
called "undercut"; this method has generally a cheap look, as it is used
with the object of saving time and expense. Carving which is treated in
this way, but instead of being "planted" close to the background, is
fixed at a little distance from it (as is the case with the lace-like
designs fitted into the hollow moldings of fifteenth-century
choir-screens), is of quite a different order, although even in this
case it can not be strictly described as undercut: it is more nearly
akin to pierced fretwork. It has, however, all the general effect of
undercut work, and is the only possible way of obtaining this effect in
wood where a large quantity of such ornament is required. The face of
such carving is generally a little convex, while the back is hollowed
out to give an equal thickness of section. The ornaments in Figs. 75,
76, and 77 are of this description, and are calculated to give great
play of light and shade, and be seen well at a considerable distance.

Undercutting in the strict and more laborious sense must be reserved for
occasions where the labor is repaid by the additional charm. It must be
considered in the light of a _tour de force_, which, on account of its
cost in the matter of time, should only be used under exceptional
circumstances, care being taken to make it clear that it is _an
exception_ to the general rule of solid carving on a solid background.

CHAPTER XXIII

PICTURE SUBJECTS AND PERSPECTIVE

The Limitations of an Art not Safely Transgressed--Aerial
Perspective Impossible in Relief--Linear Perspective only Possible
in a Limited Way.

Those vague and shadowy boundaries which separa