AMERICAN PREFACE. 
xliii 
ment of ornamental forms, a matter which can be so readily 
exemplifled by an appeal to historic usage, or by an appeal to 
nature, especially to the vegetable world, — the great source of 
decorative art. It is tbis rhythm, more tban any thing eise, tbat 
distinguishes decorative from purely pictorial art. Then tbe use 
to which the decorative object is to be put, the material of which 
it is to be made, and the mode of production, the position and 
light in which the Ornament is to be viewed after it has been 
wrought, witli many other particulars, are all to be duly consid- 
ered. About these mattcrs there is much tliat can be positively 
taught. Thus an Ornament suitable to engrave on silver may be 
altogether unsuitable to cut in granite, a material so ditferent from 
silver ; and an Ornament to be viewed in a poor light, or at a great 
elevation, requires more breadth, more large features, with less 
of fine detail, than a similar Ornament to be viewed in a strong 
light, and at short distance. The determination of such things as 
these is not at all a matter of feeling. Of course, in decoration, 
wliat it is always proper to do in a particular case is not always 
the best thing to do, and so there is ever an abundance of room 
for the exercise of msthetic judgment. Between what is positively 
good and what is positively bad, there is a wide debatable ground, 
witli which the teacher need not concern himself. He need not, 
for example, undertake to show just where Science ends, and art 
begins; just where decorative art passes from its own proper 
domain into that of pictorial art; just where industrial art and fine 
art diverge, each taking a different road : nor need he take part in 
the “ battle of styles,” thougli he should and can teach style, 
or attempt to say just how much attention should be paid to the 
precise rendering of minute details. These will always be sub- 
jects for endless discussion among tliose who delight in things 
of that sort. It is well to remember that there is nothing sin 
gulär in the debatable questions which have been mentioned. 
The naturalist, for example, finds objects he cannot affirm, with 
positive certainty, to belong to the animal or to the vegetable 
kingdom, to this species or to that. The linguist meets with the 
same puzzles. But, after one has made due allowance for all 
debatable matters, there is much relating to decorative art that 
can be taught with absolute positiveness.