se and colour, no musician will fail
to recognise a sarabande in a dance of Matisse or in the posturings of
Kellermann's clown.

As for _intensity_, with which goes _reaction_, for the first cannot
exist without the second, it is naturally brought about by the rhythmic
focusing of the subject's attention upon words, colours or notes.
Intensity is marked, for instance, by the triplets of the Venusberg
music, their continual slow billowing; it can be found, less easily, in
phrases and colours, but it must exist if the work is art. In prose it
is marked by a general nervousness of form and word:--

'Upon the crag the tower pointed to the sky like a finger of stone,
and about its base were thick bushes, which had burst forth into
flower patches of purple and scarlet. The air was heavy with their
scent.'

Here the _intensity_ is confined within the simile and the colour
scheme; the intervening space corresponds to the background of a
picture, while the final short sentence, purposely dulled, is the
_reaction_. Evidently (and all the more so as I have chosen a pictorial
effect) an analogous intensity could be obtained in a painting; the
flower patches could be exaggerated in colour to the uttermost limit of
the palette, while the reagent final sentence was figured by a filmy
treatment of the atmosphere. The limit to _intensity_ is the _key_ in
which the work is conceived. But the word _key_ must not be taken in
its purely musical sense; obviously, within the same piece the governing
motif must not be andante at the beginning and presto at the end, but in
artistic generalisations it must be taken as the spirit that informs
rather than as the technical rule which controls. Thus, in literature,
the _key_ is the attitude of the writer: if in one part of the book his
thought recalls Thackeray and in another Paul de Kock the _key_ has been
changed; and again if the left side of the picture is pointillist, the
right side cubist, the _key_ has been changed. I choose exaggerated,
almost absurd instances to make the point clear; in practice, when the
writer, the musician, or the painter appears to have seen consistently,
the key he has worked in is steadfast.

It should be said that uniformity of _key_ does not imply absence of
_reaction_; there is room, while the _key_ remains uniform, for the
juxtaposition of burlesque and romance, just as there is room in
Holbein's 'Ambassadors' for the incomprehensible objec