Scientists tell us that the whole body is replaced every seven years. Every move you make destroys cells which nature has to replace. Isn't it reasonable then to conclude that if a man should fail to eat enough lime for his body-building, his bones would suffer? If he does not get enough iron, his blood will suffer, and so on. I am convinced that most physical ailments are caused by a deficiency of the mineral elements in the body. Phosphorus and potash are necessary to human welfare. These elements are in the husk of the wheat, and when the husk is taken off in making flour, the resulting product is mostly starch. The person who lives mostly on white bread will suffer from lack of phosphorus and potash. Nothing could be better for the health of the American people than the nation-wide food campaigns the government is conducting. The educational value of these campaigns is enormous. Eat less wheat! White bread is unessential. Bran, or whole wheat bread, is far more healthful and nourishing, and contains more of the elements the human body needs. Eat more fruit. People do not eat enough fruit. Every year thousands of bushels of peaches and grapes and other fruit go to waste because the demand is not great enough to ship the entire output to the great consuming centers. Study your body's needs. Health is maintained at its proper level only so long as you eat carefully and wisely. 37. The practice of medicine in the past has been directed towards the curing of disease and physical ailments already developed. The practice of medicine in the future is to be along preventive lines. Science is showing us how to prevent infection. Science is fighting the deadly microbe which comes to us in the air we breathe, the water we drink, and the food we eat, and the infected things we touch. [Sidenote: The "Why" of Disease.] Nature has supplied the human body with a home guard of necessary bacteria, and in the circulation system are phagocytes which fight the invading microbes and generally destroy them. When the system is weakened through disease, through lack of exercise, or through improper food, disease has an easy time. I want you to remember this golden prescription. It is composed of the following: Good Air, Good Water, Good Sunshine, Good Food, Good Exercise, Good Cheer, Good Rest and Good Thought. If you take this golden prescription, you will make of yourself a giant in brain and brawn strength. You can't get health out of a bottle. You can't get the system to absorb iron if you take it in the form of tincture of iron. You can eat a pound of rust, which is oxide of iron, and none of that iron will be absorbed in the system. [Sidenote: What to Eat.] As I have explained in another chapter, you must take the mineral in the system through the vegetable route. You will get iron that will be assimilated when you eat beefsteak. Beefsteak has blood; the blood has iron. You will also get iron when you eat spinach.