Breath seems to be the sign of the beginning and the end of life. With the first breath that is drawn the body is said to be alive, and when the breath departs, the body is spoken of as dead. It is for this reason that the Yogis have called breath prana, meaning the very life. Besides this, all slight changes that take place in man's body come from an alteration in the mechanism of breath. That is why physicians in all ages have observed the signs of a person's condition in different illnesses from the beat of his pulse, which is caused by the breath.