The cause of man's weakness is the imbalance of his physical powers and desires.Strong desires make us weak, because our physical strength is not enough to satisfy our desires.Limiting our desires, then, is the same as increasing our physical strength.We are powerful when we can do more than we have to.This is the third stage of childhood, which I am dealing with now.At this time, our students are about to reach puberty, but they still haven't started to develop.During this period, a person's physical strength exceeds his desire, but I am talking about relative physical strength, not the peak of absolute physical strength.