efly upon two painters, who in this very respect of colour were the
antipodes to each other, Titian and Rubens. Are there no steady sure
principles of colour? If there be, it is impossible that such
discordant judgments can be duly and justly given.

It will be necessary to refer to something of a first principle,
before we can come to any true notion of good colouring. And it is
surprising, when we consider its simplicity, that it should, at least
practically, have escaped the due notice of artists in general.

There are two things to be first considered in colour. Its
agreeability _per se_,--its charm upon the eye; and its adaptation to
a subject,--its _expressing the sentiment_.

However well it may express the palpable substance and texture of
objects that are but parts, if it fail in these first two rules, the
colour of a picture is not good. With regard to the first, its
agreeability. Is it a startling assertion to say, that this does not
depend upon its naturalness? That it does so is a common opinion.
Aware, however, that the term naturalness would lead to a deeper
disquisition than I here mean to enter upon, I shall take it in its
common meaning, as it represents the common aspect of nature. Now,
besides that this aspect is subject to an almost infinite variety by
changes of atmosphere, and other accidents, affording the artist a
very wide range from which to select, it has a characteristic as
important as its light and its dark of colour,--_its illumination_; so
that a sacrifice (for art is a system of compensation) of one visible
truth, say a very light key, does not necessarily render a picture
less natural, if it attain that superior characteristic, which by the
other method it would not attain.

Then, again, that very variety of nature, by its multiplicity,
disposes the mind ever to look for a constant change and new effect,
so that we are not easily startled by any actual unnaturalness, unless
it be very strange indeed, and entirely out of harmony, one part with
another, as we should be were one aspect only and constantly presented
to us. This may be exemplified by a dark mirror--and, better still, by
a Claude glass, as it is called, by which we look at nature through
coloured glasses. We do not the less recognise nature--nay, it is
impossible not to be charmed with the difference, and yet not for a
moment question the truth. I am not here discussing the propriety of
using such glasses--it may be righ