because certain artists did not
appreciate certain forms of art, no artist can understand another whose
form is alien to him. There is, there must be a link between the
painter, the sculptor, the writer, the musician, the actor, between the
poet in words and the one, to-day most common, who wishes to express
himself in the deeds of his own life. For art is, we are assured
thereof, all of one stuff. A symphony and a poem may be allotropic forms
of the same matter: to use a common simile, there is red phosphorus and
there is yellow, but both are phosphorus. Likewise there are different
forms of art, but there is only one art.

It is important that artists should understand one another so that
conflict may arise from their impressions, so that they may form a
critical brotherhood. Some, to-day, are able to grasp one another's
meaning and yet find it difficult, because every form of art has its own
jargon, to express what they mean; they can grasp that the painter
equally with the writer is striving to express himself, but they fail to
phrase their appreciation and their criticism because writers cannot
talk of masses or painters of style. There stands between them a hedge
of technique; so thick is it that often they cannot see the spirit of
the works; their difficulty is one of terms. Now I do not suggest that
the musician should study Praxiteles and himself carve marble; he is
better employed expressing his own passion in the Key of C. But I do
feel that if technical terms are the preserve of each form of art,
general terms are not; that _continuity_, _rhythm_, _harmony_, to quote
but a few, have a precise meaning, that they are inherent in no form of
art because they are inherent in art itself.

The following, then, is a forlorn attempt to find the common language,
the esperanto of art. It is made up of general terms (in italics); it
represents no more than a personal point of view, and is for this reason
laid down in a tentative spirit: it is not a solution but a finger-post.
Order being a necessary antidote for the abstruse, I have divided the
terms into groups, according to their nature, to the dimension they
affect or the matter to which they refer. Following this line of thought
we find that works of art affect us in virtue of four properties: their
power, their logic, their movement, and their attitude; this leads us to
four groups of properties:--

Group A. (Volumetric): _Concentration_, _Relief_, _Density_