Anyhow, the air gets to the lungs, otherwise we die; but the lungs, which are the largest single organ in the human body and in many ways the most adaptable, have this defect, and at the same time this enormous advantage in case of disease, that a very small part of them need be used in order to supply sufficient air to the stove of combustion. We can at will (most of us do) employ the bottom part of them only, we can (with more difficulty) employ mainly the middle part, or we can with about the same difficulty employ the upper part. But since much of the health of any organ or part of the body lies in its use, for not to use an organ either passively or intentionally implies (with the only exception of those organs which are partly intended as storers of energy) its gradual atrophy, it is clearly the path of wisdom to give the lungs their proper work. For “proper work” means not exhaustion to a healthy organ but increase of strength and health. It is on the scabbarded sword that the rust grows. In the case of men, the use of the lower part of the lungs may at once be dismissed, for it is without exception natural and habitual, whereas in many women chest-breathing, owing no doubt largely to the use of the old and unscientific corsets, is correspondingly habitual; and for men the defect lies in hardly ever, except during violent effort, when one is out of breath, using the middle and upper breathing. Roughly speaking, lower breathing is accomplished by distention of the abdominal part of the apparatus, middle breathing by distention of the part of the body between the ribs, upper breathing by inflation of the chest. In what we call a long breath, and in a yawn, the breathing is complete throughout the whole of the lungs. It is this which is worth cultivation, not only for the sake of the lungs themselves, but for the sake of the control of breathing which is often useful.