The life-current is either outward, or inward, or balanced; it is regulated according to place, time, number; it is prolonged and subtle.

The technical, physical side of this has its value. In the breath, there should be right inbreathing, followed by the period of pause, when the air comes into contact with the blood, and this again followed by right outbreathing, even, steady, silent. Further, the lungs should be evenly filled; many maladies may arise from the neglect and consequent weakening of some region of the lungs. And the number of breaths is so important, so closely related to health, that every nurse's chart records it. But the deeper meaning is concerned with the currents of life; with that which goeth into and cometh out of the heart.