Life and death are two forces, constructive and destructive, and there is continual fighting between these two forces. There are times when one power wins, and the success of that power means either better health or disease and death. The body must be ready and fit to fight this battle; but the mind has a still greater part to perform, and when the mind fails to perform its part the body with all its fitness is incapable of retaining health. But if the mind is capable of keeping health, the body to a great extent obeys it. Still, harmony of both mind and body is needed to fight the battle of life.