appear to be wholly, due to the direct action of the excited sensorium.
But animals of all kinds, and their progenitors before them, when
attacked or threatened by an enemy, have exerted their utmost powers in
fighting and in defending themselves. Unless an animal does thus act,
or has the intention, or at least the desire, to attack its enemy, it
cannot properly be said to be enraged. An inherited habit of muscular
exertion will thus have been gained in association with rage; and this
will directly or indirectly affect various organs, in nearly the same
manner as does great bodily suffering.
The heart no doubt will likewise be affected in a direct manner; but it
will also in all probability be affected through habit; and all the
more so from not being under the control of the will. We know that any
great exertion which we voluntarily make, affects the heart, through
mechanical and other principles which need not here be considered; and
it was shown in the first chapter that nerve-force flows readily
through habitually used channels, through the nerves of voluntary or
involuntary movement, and through those of sensation. Thus even a
moderate amount of exertion will tend to act on the heart; and on the
principle of association, of which so many instances have been given,
we may feel nearly sure that any sensation or emotion, as great pain or
rage, which has habitually led to much muscular action, will
immediately influence the flow of nerve-force to the heart, although
there may not be at the time any muscular exertion.
The heart, as I have said, will be all the more readily affected
through habitual associations, as it is not under the control of the
will. A man when moderately angry, or even when enraged, may command
the movements of his body, but he cannot prevent his heart from beating
rapidly. His chest will perhaps give a few heaves, and his nostrils
just quiver, for the movements of respiration are only in part
voluntary. In like manner those muscles of the face which are least
obedient to the will, will sometimes alone betray a slight and passing
emotion. The glands again are wholly independent of the will, and a man
suffering from grief may command his features, but cannot always
prevent the tears from coming into his eyes. A hungry man, if tempting
food is placed before him, may not show his hunger by any outward
gesture, but he cannot check the secretion of saliva.
Under a transport of Joy or of vivid Pleasure, there is a strong
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