Breath in this way acts like a ball in tennis thrown from one side to the other, and the force of its movement comes from the side from which it is directed. Therefore when it is directed from the body to the mind the mind becomes subject to the influence of the body, but when from the side of the mind it is directed toward the body, in this case the body becomes subject to the mind. Very often dervishes and faqirs in the East, many of whom live upon alms and go several days without food and spend many nights in sleepless vigil, do things which are difficult for a wrestler, a boxer, or any other muscular person.