h life most men
find it difficult to suppress irritation on similar occasions. In the
animal world the most furious excitement of this instinct is provoked
in the male of many species by any interference with the satisfaction
of the sexual impulse.[2]

[Footnote 2: McDougall: _loc. cit._, p. 60.]

This original tendency to fight is very persistent in human
beings, but is susceptible of direction, and is not, in civilized
life, frequently revealed in its crude and direct form, save
among children and among adults under intense provocation
and excitement. Occasionally, however, pugnacity is displayed
in its simple animal form. "Man shares with many
of the animals the tendency to frighten his opponent by loud
roars or bellowings.... Many a little boy has, without example
or suggestion, suddenly taken to running with open
mouth to bite the person who has angered him, much to the
distress of his parents."[1] As the individual grows older, he
learns to control the outward and immediate expression of
this powerful and persistent human trait. He learns in his
dealings with other people not to give way, when frustrated
in some action or ambition, to mere animal rage. The customs
and manners to which a child is early subjected in
civilized intercourse are effective hindrances to uncontrolled
display of anger and pugnacity; superior intelligence and
education find more refined ways than kicking, pummeling, and
scratching of overcoming the interferences of others. But
even in gentle and cultured persons, an insult, a disappointment,
a blow will provoke the tell-tale signs of pugnacity and
anger, the flushing of the cheeks, the flash of the eye, the
incipient clenching of the fists, the compressing of the teeth and
lips, and the trembling of the voice. We substitute sarcasm
for punching, and find subtly civilized, and, in the long run,
more terrible, ways than bruises of punishing those who oppose
us in our play, our passions, our professions. But our
ancestors were beasts of prey, and there is still "fighting
in our blood."

[Footnote 1: McDougall: _loc. cit._, p. 61.]

The fighting instinct is aroused by both personal and impersonal
situations, and is occasioned even by very slight interferences,
and even when the author of the interference is
neither human nor animate. Quite intelligent men have been
known to kick angrily at a door as if from pure malice it refused
to open. Irate commuters have glared vindictively at
tr