Scientific selection and combination of food and drink. Judicious fasting. Hydrotherapy (water cure). Light and air baths, friction. Chiropratic or osteopathy, massage, and other manipulative treatment. Correct breathing, curative gymnastics. Such medicinal remedies as will build up the blood on a normal basis and supply the system with the all-important mineral salts in organic form. In the following chapters I shall endeavor to show that all the different forms, phases and phenomena of disease arising within the human organism, provided they are not caused by accident or external conditions unfavorable to the existence of human life, can be attributed to one or more of three primary causes (as outlined in Tables I and II). When we succeed in proving that all disease originates from a few simple causes, it will not seem so strange and improbable that all disease can be cured by a few simple, natural methods of living and of treatment. If Nature Cure can accomplish this, it establishes its right to be classed with the exact sciences. The Three Primary Causes of Disease We shall now consider the three primary causes of disease one by one. Lowered Vitality There is a well-defined limit to the running of a watch. When the wound spring has spent its force, the mechanism stops. So also the living forms of vegetable, animal and human life seem to be wound by Nature to run a certain length of time, in accordance with the laws governing their growth and development. Even the healthiest of animals living in the most congenial surroundings in the freedom of Nature do not much exceed their allotted span of life, nor do they fall much below it. As a rule, the longer the period between birth and maturity, the longer the life of the animal. All the different families of mammalia, when living in freedom, live closely up to the life period allotted to them by Nature. Man is the only exception. It is claimed that according to the laws of longevity his average length of life should be considerably over one hundred years, while according to life insurance statistics, the average is at present [1913] thirty-seven years. This shows an immense discrepancy between the possible and the actual longevity of man. Even this brief span of life means little else than weakness, physical and mental suffering and degeneracy for the majority of mankind. Visiting physicians of the public schools in our large cities report that seventy-five percent of all school children show defective health in some way. Diagnosis from the Eye proves that the remaining twenty-five percent are also more or less affected by hereditary and acquired disease conditions. Christian Science says, "There is no disease." Nature's records in the iris of the eye say there is no perfect health.