the origin of much of nervousness is to be found, and that on what
may be called the physical basis of emotion.

What can emotion produce that is pathological, detrimental to
well-being? We may start with the grossest, simplest manifestations. It
may entirely upset digestion, as in the vomiting of disgust and
excitement. Or, in lesser measure, it may completely destroy the
appetite, as occurs when a disturbing emotion arises at mealtime. This
is probably brought about by the checking of the gastric secretions.
(Cannon's work; Pavlow's work.)

It may check the secretion of milk in the nursing mother, or it may
change the quality of the milk so that it almost poisons the infant. It
may cause the bladder and bowels to be evacuated, or it may prevent
their evacuation.

It may so change the supply of blood in the body as to leave the head
without sufficient quantity and thus bring about a fainting spell;
_i.e._ may absolutely deprive the victim of consciousness. In lesser
degree it causes the blush, a visible manifestation of emotion often
very distressing.

It may completely abolish sex power in the male, or it may bring about
sex manifestations which the victim would almost rather die than show.

It may completely deenergize so that neither interest, enthusiasm, or
power remains. This is a familiar effect of sorrow but occurs in lesser
degree with the form of fear called worry.

The fact is that emotion is an intense bodily response to a situation
which when perceived is the state of feeling. This intense bodily
response, involving the very minutest tissues of the body, may increase
the available energy, may help the bodily functioning, may stimulate the
"psychical" processes, but also it may deenergize to an extraordinary
degree, it may interfere with every function, including thought and
action. It may surely produce acute illness, and it may, though rarely,
produce death.

Moreover, it is extraordinarily contagious. Every one knows how a hearty
laugh spreads, and how quick the response to a smile. Indeed, emotion
has probably for one of its main functions the producing of an effect
on some one else, and all the world uses emotion for this purpose. Anger
is used to produce fear, sorrow to evoke sympathy, fear is to bring
about relenting, a smile and laughter, friendliness, except where one
smiles or laughs _at_ some one, and then its design is to bring sorrow,
anger, or pain. The leader maintains a hopeful, joyo