, she contrives to bring darkness into light, and light into
darkness; and that so sharply and decisively, that at the very instant
when one object changes from light to dark, the thing relieved upon it
will change from dark to light, and yet so subtly that the eye will not
detect the transition till it looks for it. The secret of a great part
of the grandeur in all the noblest compositions is the doing of this
delicately in _degree_, and broadly in _mass_; in color it may be done
much more decisively than in light and shade, and, according to the
simplicity of the work, with greater frankness of confession, until, in
purely decorative art, as in the illumination, glass-painting, and
heraldry of the great periods, we find it reduced to segmental accuracy.
Its greatest masters, in high art, are Tintoret, Veronese, and Turner.

Sec. XXVIII. Together with this great principle of quartering is
introduced another, also of very high value as far as regards the delight
of the eye, though not of so profound meaning. As soon as color began to
be used in broad and opposed fields, it was perceived that the mass of it
destroyed its brilliancy, and it was _tempered_ by chequering it with
some other color or colors in smaller quantities, mingled with minute
portions of pure white. The two moral principles of which this is the
type, are those of Temperance and Purity; the one requiring the fulness
of the color to be subdued, and the other that it shall be subdued
without losing either its own purity or that of the colors with which it
is associated.

Sec. XXIX. Hence arose the universal and admirable system of the diapered
or chequered background of early ornamental art. They are completely
developed in the thirteenth century, and extend through the whole of
the fourteenth gradually yielding to landscape, and other pictorial
backgrounds, as the designers lost perception of the purpose of their
art, and of the value of color. The chromatic decoration of the Gothic
palaces of Venice was of course founded on these two great principles,
which prevailed constantly wherever the true chivalric and Gothic spirit
possessed any influence. The windows, with their intermediate spaces of
marble, were considered as the objects to be relieved, and variously
quartered with vigorous color. The whole space of the brick wall was
considered as a background; it was covered with stucco, and painted in
fresco, with diaper patterns.

Sec. XXX. What? the re