the
chemistry of skies. We deal with color as with sound--so far ruling the
power of the light, as we rule the power of the air, producing beauty
not necessarily imitative, but sufficient in itself, so that, wherever
color is introduced, ornamentation may cease to represent natural
objects, and may consist in mere spots, or bands, or flamings, or any
other condition of arrangement favorable to the color.

70. B. Conventionalism by cause of inferiority.--In general,
ornamentation is set upon certain services, subjected to certain
systems, and confined within certain limits; so that its forms require
to be lowered or limited in accordance with the required relations. It
cannot be allowed to assume the free outlines, or to rise to the
perfection of imitation. Whole banks of flowers, for instance, cannot be
carved on cathedral fronts, but only narrow moldings, having some of the
characters of banks of flowers. Also, some ornaments require to be
subdued in value, that they may not interfere with the effect of others;
and all these necessary _inferiorities_ are attained by means of
departing from natural forms--it being an established law of human
admiration that what is most representative of nature shall, _caeteris
paribus_, be most attractive.

All the various kinds of ornamentation, consisting of spots, points,
twisted bands, abstract curves, and other such, owe their peculiar
character to this conventionalism "by cause of inferiority."

71. C. Conventionalism by cause of means.--In every branch of art, only
so much imitation of nature is to be admitted as is consistent with the
ease of the workman and the capacities of the material. Whatever
shortcomings are appointed (for they are more than permitted, they are
in such cases appointed, and meritorious) on account of the
untractableness of the material, come under the head of "conventionalism
by cause of means."

These conventionalities, then, being duly understood and accepted, in
modification of the general law, that law will be, that the glory of all
ornamentation consists in the adoption or imitation of the beauties of
natural objects, and that no work can be of high value which is not full
of this beauty. To this fourth proposition, modern architects have not
ventured to make any serious resistance. On the contrary, they seem to
be, little by little, gliding into an obscure perception of the fact,
that architecture, in most periods of the world, had sculpture upo