analysis of sound, by the nerve organism of the ear,
that of colour upon a synthesis of various pitches
heard together; in both cases the ear is unconscious
of what it is doing, perceiving only the result,--the
pitch in one case, the colour in the other. Yet the
synthesis which results in colour is less abstruse than
the analysis which results in pitch; by attention the
ear can be brought to perceive the harmonic notes,
out of the combination of which with the ground
note the colour has arisen; whereas no attention will
enable us to perceive the separate moments of sound
which together produce a perceived pitch; these are
entirely below consciousness, and the pitch itself is
the first and only thing heard. For, if the ear heard
the separate beats in the periodic vibrations which
determine the pitch, and composed the pitch out of
them as heard pulses, we ought by an effort of atten-
tion to be able to hear the several beats in one pitch,
just as we are to hear the harmonies which compose
the colour. This attentive perception however de-
stroys the pleasure of perceiving colour. The com-
bination must be perceived unanalysed, in order to
the pleasurable effect of colour on the ear. This
gives the colour a less intellectual character than the
pitch; for greater differences are combined together,
the act of combination being equally unperceived.
Yet the different pitches which are combined into
colour give the possibility of an intellectual mea-
surement when two colours are heard together, the
ground tones of which may be either concordant or
discordant with each other. This gives a second kind
of harmony, founded on the comparison of colours,
in addition to that founded on the comparison of
pitches. Notes of the same pitch have different har-

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