The conditions of life are that the organism should be able to adjust itself continually to its environment. Any individual, to do this for long, needs either very great intelligence or very great luck. His chief physical asset is elasticity, the power of compensation and recuperation. This water, by kidneys, lungs, and skin, constantly cleanses us, and carries off most of our waste and noxious matter. Disease and accident apart, we die of arterio-sclerosis caused by the gradual deposits of insoluble salts which harden the arteries and destroy the elasticity which enables them to adjust themselves to new conditions.
Old age is simply a solidification of the tissues, all of which become hard, dry and brittle.
Exercise helps us to sluice our sewers, but we must flush them well with water to dissolve mineral waste. We must avoid the ingestion of foods likely to leave insoluble deposits. But there is another cause of decay, cause also in part of this poisoning. Our organs would repair themselves perfectly, if they were given sufficient rest. In their haste they absorb the first material to hand, be it good or bad.