ely, we have a broken, a fragmentary effect, as that of
zigzag, where all is dropping and picking up again of associated
motions; in the straight line, much prolonged, we have a gradual
and inexorable rending of these tendencies to associated
movements.

In the curves we call flowing and graceful, we have, on the
contrary, a more natural and rhythmical set of movements in the
optic muscles; and certain points in the various gyrations make
rhymes and assonances, as it were, to the eye that reaches them.
We find ourselves at every turn reawakening, with a variation, the
sense of the previous position. It is easy to understand by analogy
with the superficially observed conditions of pleasure, that such
rhythms and harmonies should be delightful. The deeper question
of the physical basis of pleasure we have not intended to discuss.
Suffice it that measure, in quantity, in intensity, and in time, must
involve that physiological process, whatever it may be, the
consciousness of which is pleasure.

_Symmetry._

Sec. 22. An important exemplification of these physiological
principles is found in the charm of symmetry. When for any reason
the eye is to be habitually directed to a single point, as to the
opening of a gate or window, to an altar, a throne, a stage, or a
fireplace, there will be violence and distraction caused by the
tendency to look aside in the recurring necessity of looking
forward, if the object is not so arranged that the tensions of eye are
balanced, and the centre of gravity of vision lies in the point which
one is obliged to keep in sight. In all such objects we therefore
require bilateral symmetry. The necessity of vertical symmetry is
not felt because the eyes and head do not so readily survey objects
from top to bottom as from side to side. The inequality of the upper
and lower parts does not generate the same tendency to motion, the
same restlessness, as does the inequality of the right and left sides
of an object in front of us. The comfort and economy that comes
from muscular balance in the eye, is therefore in some cases the
source of the value of symmetry.[5]

In other cases symmetry appeals to us through the charm of
recognition and rhythm. When the eye runs over a facade, and
finds the objects that attract it at equal intervals, an expectation,
like the anticipation of an inevitable note or requisite word, arises
in the mind, and its non-satisfaction involves a shock. This shock,
if caused b