r we never can see it entirely
separated from some foreign influence. In a picture it would be
perhaps best to consider that the _proper_ colour which would be
proper to the half-tone, whether modified by aerial perspective or
not. He considers that _proper_ colour is not shown mostly in objects
in the foreground, for there the light which destroys it is most
powerful; light destroys proper colour, and substitutes its own. "It
is the perfect understanding of this interesting principle, which
renders the works of Rubens, and of his best scholars, so superior for
their magic truth of colour. It is this which explains why they make
the colour of the blood to appear through the fine and transparent
skin of their Flemings, particularly of the women, only in proportion
as the effect of the light is lost in the retiring parts; and why the
red prevails more in these parts in general, which are illuminated
only by a reflected light too feeble to change the natural colour. The
latter may often be even strengthened by the colour of the object from
which the reflected light proceeds, which happens when one flesh part
is reflected upon another, as may be remarked more particularly
towards the extremities."

The following quotation is well worth considering--the observation it
contains is new. "As to the influence of light upon the local colours,
one of the plainest proofs of it is, that the colour of objects seen
in broad day, diminishes in force the more that the sun enlightens the
distant plain on which they are placed. This observation, and many
other analogous ones, convince me that the light in a picture in
general exerts a greater influence upon the local colours than even
the air, although those who have written upon the art seem to
attribute the local colours exclusively to the interposition of the
air and the vapours with which it is charged. The above remark, though
useful to all painters, becomes the more indispensable to those who
have to do with landscape, seeing that without attention to it, the
aerial perspective would render useless, by a false and mannered
representation, the just proportions and the exact contours dictated
by linear perspective. Another remark, not less interesting, is, that
the colour of cast shadows depends, beyond every thing, on that of the
light, and consequently on the state of the atmosphere and the time of
the day, as well as the season of the year." Hence is it that the
brown shadows of a