"The human fetus is born upside down. But it is not true that a child becomes upright after birth. Observe the feet of children and young people when they are at rest. The feet are nearly always higher than the head, No matter how hard he may try, the growing boy, and particularly girl, cannot keep the feet down. The fetal position is very strong. It takes eighteen to twenty years for the feet finally to accept the ground as their normal home. It is my hypothesis that you can judge maturity exactly by the relationship of the feet to the ground."