This essential connection between colour and form brings us to
the question of the influences of form on colour. Form alone,
even though totally abstract and geometrical, has a power of
inner suggestion. A triangle (without the accessory consideration
of its being acute-or obtuse-angled or equilateral) has a
spiritual value of its own. In connection with other forms, this
value may be somewhat modified, but remains in quality the same.
The case is similar with a circle, a square, or any conceivable
geometrical figure. [Footnote: The angle at which the triangle
stands, and whether it is stationary or moving, are of importance
to its spiritual value. This fact is specially worthy of the
painter's consideration.] As above, with the red, we have here a
subjective substance in an objective shell.

The mutual influence of form and colour now becomes clear. A
yellow triangle, a blue circle, a green square, or a green
triangle, a yellow circle, a blue square--all these are different
and have different spiritual values.

It is evident that many colours are hampered and even nullified
in effect by many forms. On the whole, keen colours are well
suited by sharp forms (e.g., a yellow triangle), and soft, deep
colours by round forms (e.g., a blue circle). But it must be
remembered that an unsuitable combination of form and colour is
not necessarily discordant, but may, with manipulation, show the
way to fresh possibilities of harmony.

Since colours and forms are well-nigh innumerable, their
combination and their influences are likewise unending. The
material is inexhaustible.