the artistic imagination to select and to amplify. Already many
years ago the scientist Helmholtz said, “Our system of scales
and of harmonic tissues does not rest upon unalterable natu-
ral laws, but is partly at least the result of aesthetic principles
of selection, which have already changed, and will change still
further with the progressive development of humanity."[293] In
other words the limits of receptivity of the human ear cannot
be foreseen nor can the workings of the artistic imagination be
prescribed. The so-called Chord of Nature,[294] consisting of
the overtones struck off by any sounding body, and re-enforced
on the pianoforte with its large sounding board, contains in
epitome this basic material of music; and the several octaves
represent in a striking manner the harmonic combinations used
at different periods of development. Thus during the early cen-
turies nothing but triads were in use; only gradually were 7th
chords—those of four factors—introduced. Wagner was the first
to realize the possibilities of chords of the 9th, 11th, and 13th.
In Debussy these combinations are used as freely as triads,e.g.
[Music:Pelléas et Mélisande]
[Music:La fille aux cheveux de lin]
[Music:Reflets dans l’eau]
and he has gone far beyond anything known before in a subtle
use of the extreme dissonant elements, his sensitive imagination
evidently hearing sounds hitherto unrealized. This surmise is
corroborated by Debussy’s own statement that, while serving as
a young man on garrison duty, he took great delight in listening
to the overtones of bugles and of the bells from a nearby convent.
This chromatic style had been anticipated by Chopin whose use
of the harmonic series in those prismatic, spray-like groups of su-
peradded tones is such a striking feature in his pianoforte works.
There is, therefore, nothing outré or bizarre in Debussy’s idiom;
it is but a logical continuation of former tendencies. His works
show great variety and comprise pianoforte pieces, many songs,
a remarkable string quartet, some daringly original tone-poems
for full orchestra, several cantatas, and—most unique of all—his
opera ofPelléas et Mélisande, based on the well-known play by
Maeterlinck. A few comments may profitably be made on each
of these types. With few exceptions all his pianoforte pieces
have suggestive titles,e.g.,Reflets dans l’eau,Jardins sous la
pluie,La soirée dans Grenade,Poissons d’or,Voiles,Le vent