These two simple forms of feeling perhaps arose in the beginning in
connection with the act of taking food. It is known that if a drop of
acid touches an amoeba, the animal shrinks, contracts, and tries to
withdraw from the death-bringing acid. On the other hand, if a particle
of a substance that is suitable for food touches the animal, it takes
the particle within itself. The particle is life-giving and brings
pleasure.

=The Emotions.= Pleasure and displeasure are the simple feelings. Most
situations in life bring about very complex feeling states known as
_emotions_. The emotions are made up of pleasure or displeasure mixed
or compounded with the sensations from the bodily reactions.

The circulatory system, the respiratory system, and nearly all the
involuntary organs of the body form a great sounding board which
instantly responds in various ways to the situations of life. When the
youth sees the pretty maiden and when he touches her hand, his heart
pumps away at a great rate, his cheeks become flushed, his breathing is
paralyzed, his voice trembles. He experiences the emotion of love. The
state is complex indeed. There is pleasantness, of course, but there is
in addition the feeling of all the bodily reactions.

When the mother sees her dead child lying in its casket, her head falls
over on her breast, her eyes fill with tears, her shoulders droop, her
chest contracts, she sobs, her breathing is spasmodic. Nearly every
organ of the body is affected in one way or another. The state is
_unpleasant_, but there is also the feeling of the manifold bodily
reactions.