ans that Art adds to its processes of selection
and exclusion a process of _inclusion,_ safeguarding aesthetic
contemplation by drawing whatever is not wholly refractory into
that contemplation's orbit. This turning of non-aesthetic interests
from possible competitors and invaders into co-operating allies is an
incomparable multiplying factor of aesthetic satisfaction, enlarging
the sphere of aesthetic emotion and increasing that emotion's volume
and stability by inclusion of just those elements which would have
competed to diminish them. The typical instance of such a possible
competitor turned into an ally, is that of the cubic element, which I
have described (p. 85) as the first and most constant intruder from
the thought of _Things_ into the contemplation of _Shapes._ For the
introduction into a picture of a suggested third dimension is what
prevents our _thinking away from_ a merely two-dimensional aspect
by supplying subsidiary imaginary aspects susceptible of being
co-ordinated to it. So perspective and modelling in light and shade
satisfy our habit of locomotion by allowing us, as the phrase is, _to
go into_ a picture; and _going into,_ we remain there and establish
on its imaginary planes schemes of horizontals and verticals besides
those already existing on the real two-dimensional surface. This
addition of shapes due to perspective increases the already existing
dramas of empathy, instead of interrupting them by our looking
away from the picture, which we should infallibly do if our
exploring and so to speak _cubic-locomotor_ tendencies were not
thus employed inside the picture's limits.

This alliance of aesthetic contemplation with our interest in cubic
existence and our constant thought of locomotion, does more
however than merely safeguard and multiply our chances of
empathic activity. It also increases the sensory discrimination, and
hence pleasureableness, of colour, inasmuch as colour becomes,
considered as light and shade and _values,_ a suggestion of
three-dimensional _Things_ instead of merely a constituent of
two-dimensional _Shapes._ Moreover, one easily tires of "following"
verticals and horizontals and their intermediate directions; while
empathic imagination, with its dynamic feelings and frequent
semi-mimetic accompaniments, requires sufficient intervals of repose;
and such repose, such alternation of different mental functions,
isprecisely afforded by thinking in terms of cubic existence.
A