An emotion may be very strong, but it will have little tendency to
induce movements of any kind, if it has not commonly led to voluntary
action for its relief or gratification; and when movements are excited,
their nature is, to a large extent, determined by those which have
often and voluntarily been performed for some definite end under the
same emotion. Great pain urges all animals, and has urged them during
endless generations, to make the most violent and diversified efforts
to escape from the cause of suffering. Even when a limb or other
separate part of the body is hurt, we often see a tendency to shake it,
as if to shake off the cause, though this may obviously be impossible.
Thus a habit of exerting with the utmost force all the muscles will
have been established, whenever great suffering is experienced. As the
muscles of the chest and vocal organs are habitually used, these will
be particularly liable to be acted on, and loud, harsh screams or cries
will be uttered. But the advantage derived from outcries has here
probably come into play in an important manner; for the young of most
animals, when in distress or danger, call loudly to their parents for
aid, as do the members of the same community for mutual aid.
Another principle, namely, the internal consciousness that the power or
capacity of the nervous system is limited, will have strengthened,
though in a subordinate degree, the tendency to violent action under
extreme suffering. A man cannot think deeply and exert his utmost
muscular force. As Hippocrates long ago observed, if two pains are felt
at the same time, the severer one dulls the other. Martyrs, in the
ecstasy of their religious fervour have often, as it would appear, been
insensible to the most horrid tortures. Sailors who are going to be
flogged sometimes take a piece of lead into their mouths, in order to
bite it with their utmost force, and thus to bear the pain. Parturient
women prepare to exert their muscles to the utmost in order to relieve
their sufferings.
We thus see that the undirected radiation of nerve-force from the
nerve-cells which are first affected the long-continued habit of
attempting by struggling to escape from the cause of suffering and the
consciousness that voluntary muscular exertion relieves pain, have all
probably concurred in giving a tendency to the most violent, almost
convulsive, movements under extreme suffering; and such movements,
including those of the vocal organs, are universally recognized as
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