d E, when combined, to give the same sensation as the
single intermediate note D. Nothing of the kind! Were it so, music
would be very different from what it is, if indeed it were possible at
all. But the real difference between the two senses at this point is
better expressed by saying that D does not give the effect of a
combination of C and E, or, in general, that no one note ever gives
the effect of a combination or blend of notes higher and lower than
itself. Homogeneous orange light gives the sensation of a blend of red
and yellow; but there is nothing like this in the auditory sphere. In
light, some wave-lengths give the effect of simple colors, as red and
yellow; and other wave-lengths the effect of blends, as greenish
yellow or bluish {233} green; but in sound, every wave-length gives a
tone which seems just as elementary as any other.

There is nothing in auditory sensation to correspond to white, no
simple sensation resulting from the combined action of all
wave-lengths. Such a combination gives noise, but nothing that seems
particularly simple. There is nothing auditory to correspond with
black, for silence seems to be a genuine absence of sensation. There
are no complementary tones like the complementary colors, no tones
that destroy each other instead of blending. In a word, auditory
sensation tallies with its stimulus much more closely than visual
sensation does with its; and the main secret of this advantage of the
sense of hearing is that it has a much larger number of elementary
responses. Against the six elementary visual sensations are to be set
auditory elements to the number of hundreds or thousands. From the
fact that every distinguishable pitch gives a tone which seems as
simple and unblended as any other, the conclusion would seem to be
that each was an element; and this would mean thousands of elements.
On the other hand, the fact that tones close together in pitch sound
almost alike may mean that they have elements in common and are thus
themselves compounds; but still there would undoubtedly be hundreds of
elements.

Both sight and hearing are served by great armies of sense cells, but
the two armies are organized on very different principles. In the
retina, the sense cells are spread out in such a way that each is
affected by light from one particular direction; and thus the retina
gives excellent space information. But each retinal cell is affected
by any light that happens to come from i