An animal of the higher class can live several days without water, several weeks without food, but only a very few minutes without oxygen. When the blood becomes surcharged with carbonic acid gas, and oxygen is refused admittance to the lungs, life ceases in about five or six minutes. From this it can easily be seen how important it is to have a proper supply of oxygen. Acute deprivation of this element is immediately fatal, and chronic deprivation of a good supply helps to produce early deterioration and premature death. The lungs can easily be kept in good condition, and when we ponder on the beautiful and effective way in which nature has equipped us with a respiratory apparatus and an inexhaustible store of oxygen, surely we must understand the folly of not helping ourselves to what is so vital, yet absolutely free. Wrong eating and impure air are largely responsible for all kinds of respiratory troubles, from a simple cold to the most aggravated form of pulmonary tuberculosis. Exercise and deep breathing will to a great extent antidote overeating, but there is a limit beyond which the lungs refuse to tolerate this form of abuse. Experiments have shown that if the carbonic acid gas thrown off daily by an adult male were solidified, it would amount to about seven ounces of solid carbon, which comes from fats, sugars and starches that are burned in the body. It is well to remember that there are various forms of burning or combustion. Rapid combustion is exemplified in stoves and furnaces, where the carbon of coal or wood rapidly and violently unites with oxygen. Slow combustion takes place in the rotting of wood, the rusting of iron and steel and the union of oxygen with organic matter in animal bodies. Both processes are the same, varying only in rapidity and intensity. People who daily give off seven ounces of carbon are overworking their bodies. They take in too much food and consequently force too great combustion. This forcing has evil effects on the system, for under forced combustion the body is not able to clean itself thoroughly. Some of the soot remains in the flues (the blood-vessels) and is deposited in the various parts of the engine (the body). Result: Hardening, which means loss of elasticity and aging of the body. Aging of the body results in deterioration of the mind. Proper breathing is fine, but unless it is also accompanied by proper eating it does not bring the best results.