's nest out of marble would be physically impossible, and to reach
any approximate expression of its structure would require prolonged and
intolerable labor. Therefore, all sculpture which set itself to carving
birds' nests as an end, or which, if a bird's nest were required of it,
carved it to the utmost possible point of realization, would be debased.
Nothing but the general form, and as much of the fibrous structure as
could be with perfect ease represented, ought to be attempted at all.

But more than this. The workman has not done his duty, and is not
working on safe principles, unless he even so far _honors_ the materials
with which he is working as to set himself to bring out their beauty,
and to recommend and exalt, as far as lie can, their peculiar qualities.
If he is working in marble, he should insist upon and exhibit its
transparency and solidity; if in iron, its strength and tenacity; if in
gold, its ductility; and he will invariably find the material grateful,
and that his work is all the nobler for being eulogistic of the
substance of which it is made. But of all the arts, the working of glass
is that in which we ought to keep these principles most vigorously in
mind. For we owe it so much, and the possession of it is so great a
blessing, that all our work in it should be completely and forcibly
expressive of the peculiar characters which give it so vast a value.

These are two, namely, its DUCTILITY when heated, and TRANSPARENCY when
cold, both nearly perfect. In its employment for vessels, we ought
always to exhibit its ductility, and in its employment for windows, its
transparency. All work in glass is bad which does not, with loud voice,
proclaim one or other of these great qualities.

Consequently, _all cut glass_ is barbarous: for the cutting conceals its
ductility, and confuses it with crystal. Also, all very neat, finished,
and perfect form in glass is barbarous: for this fails in proclaiming
another of its great virtues; namely, the ease with which its light
substance can be moulded or blown into any form, so long as perfect
accuracy be not required. In metal, which, even when heated enough to be
thoroughly malleable, retains yet such weight and consistency as render
it susceptible of the finest handling and retention of the most delicate
form, great precision of workmanship is admissible; but in glass, which
when once softened must be blown or moulded, not hammered, and which is
liable to lose,