Being an only child is a disease in itself.

Muscles are in a most intimate and peculiar sense the organs of the will.

Civilization is so hard on the body that some have called it a disease, despite the arts that keep puny bodies alive to a greater average age, and our greater protection from contagious and germ diseases.

Abundance and vigor of automatic movements are desirable, and even a considerable degree of restlessness is a good sign in young children.

Adolescence is a new birth, for the higher and more completely human traits are now born.

Every theory of love, from Plato down, teaches that each individual loves in the other sex what he lacks in himself.

Man is largely a creature of habit, and many of his activities are more or less automatic reflexes from the stimuli of his environment.

Of all work-schools, a good farm is probably the best for motor development.

The man of the future may, and even must, do things impossible in the past and acquire new motor variations not given by heredity.

The years from about eight to twelve constitute a unique period of human life.