remote and indirect manner. So again with the movements coming under
our third principle; these, in as far as they are influenced by
nerve-force readily passing along habitual channels, have been
determined by former and repeated exertions of the will. The effects
indirectly due to this latter agency are often combined in a complex
manner, through the force of habit and association, with those directly
resulting from the excitement of the cerebro-spinal system. This seems
to be the case with the increased action of the heart under the
influence of any strong emotion. When an animal erects its hair,
assumes a threatening attitude, and utters fierce sounds, in order to
terrify an enemy, we see a curious combination of movements which were
originally voluntary with those that are involuntary. It is, however,
possible that even strictly involuntary actions, such as the erection
of the hair, may have been affected by the mysterious power of the
will.
Some expressive movements may have arisen spontaneously, in association
with certain states of the mind, like the tricks lately referred to,
and afterwards been inherited. But I know of no evidence rendering this
view probable.
The power of communication between the members of the same tribe by
means of language has been of paramount importance in the development
of man; and the force of language is much aided by the expressive
movements of the face and body. We perceive this at once when we
converse on an important subject with any person whose face is
concealed. Nevertheless there are no grounds, as far as I can discover,
for believing that any muscle has been developed or even modified
exclusively for the sake of expression. The vocal and other
sound-producing organs, by which various expressive noises are
produced, seem to form a partial exception; but I have elsewhere
attempted to show that these organs were first developed for sexual
purposes, in order that one sex might call or charm the other. Nor can
I discover grounds for believing that any inherited movement, which now
serves as a means of expression, was at first voluntarily and
consciously performed for this special purpose, like some of the
gestures and the finger-language used by the deaf and dumb. On the
contrary, every true or inherited movement of expression seems to have
had some natural and independent origin. But when once acquired, such
movements may be voluntarily and consciously employed as a means of
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