are only annoying, and for the same reason. The eye longs
for repose in some serene radiance or stately sequence, while the ear
delights in contrast and continual change. It may be that as the eye
becomes more educated it will demand more movement and complexity, but
a certain stillness and serenity are of the very nature of light,
as movement and passion are of the very nature of sound. Music is a
seeking--"love in search of a word"; light is a finding--a "divine
covenant."

With attention still focussed on the differences rather than the
similarities between the musical art and a new art of mobile color,
we come next to the consideration of the matter of form. Now form
is essentially of space: we speak about the "form" of a musical
composition, but it is in a more or less figurative and metaphysical
sense, not as a thing concrete and palpable, like the forms of space.
It would be foolish to forego the advantage of linking up form with
colour, as there is opportunity to do. Here is another golden ball to
juggle with, one which no art purely in time affords. Of course it is
known that musical sounds weave invisible patterns in the air, and to
render these patterns perceptible to the eye may be one of the more
remote and recondite achievements of our uncreated art. Meantime,
though we have the whole treasury of natural forms to draw from, of
these we can only properly employ such as are _abstract_. The reason
for this is clear to any one who conceives of an art of mobile color,
not as a moving picture show--a thing of quick-passing concrete
images, to shock, to startle, or to charm--but as a rich and various
language in which light, proverbially the symbol of the spirit, is
made to speak, through the senses, some healing message to the soul.
For such a consummation, "devoutly to be wished," natural forms--forms
abounding in every kind of association with that world of materiality
from which we would escape--are out of place; recourse must be had
rather to abstract forms, that is, geometrical figures. And because
the more remote these are from the things of sense, from knowledge and
experience, the projected figures of four-dimensional geometry would
lend themselves to these uses with an especial grace. Color without
form is as a soul without a body; yet the body of light must be
without any taint of materiality. Four-dimensional forms are as
immaterial as anything that could be imagined and they could be made
to serve