I

THE preceding pages have set forth the concrete facts of
visible beauty, and the explanation of our feelings about it.
It is also interesting, however, to see how these principles
are illustrated and confirmed in the masterpieces of art. A
statistical study, undertaken some years ago with the purpose
of dealing thus with the hypothesis of substitutional symmetry
in pictorial composition, has given abundance of material,
which I shall set forth, at otherwise disproportionate length,
as to a certain extent illustrative of the methods of such
study. It is clear that this is but one of many possible
investigations in which the preceding psychological theories
may be further illuminated. The text confines itself to
pictures; but the functions of the elements of visual form
are valid as well for all visual art destined to fill a bounded
area. The discussion will then be seen to be only ostensibly
limited in its reference. For picture might always be read
space arrangement within a frame.

In the original experimental study of space arrangements, the
results of which were given at length on page 111, the elements
of form in a picture were reduced to SIZE or MASS, DEPTH in the
third dimension, DIRECTION, and INTEREST. Direction was further
analyzed into direction of MOTION or ATTENTION (of persons or
objects in the picture), an ideal element, that is; and direction
of LINE. For the statistical study, a given picture was then
divided in half by an imaginary vertical line, and the elements
appearing on each side of this line were set off against each