Hygiene is properly defined as that branch of biology which designates the conditions upon which health depends and the means by which it may be sustained in all its virtue and purity while we have it, and the means upon which its restoration rests when we have lost it. It is the scientific application of the principles of nature in the preservation and restoration of health. We may also define Hygiene as the science of normal vital development. It comprehends all the laws that determine the changes in living organisms and all the conditions which conduce to or interfere with normal growth and sustenance. It traces these conditions to the unerring laws of nature and thereon establishes its science of life. It demonstrates the great primary principle of human action, that all permanent good, all enduring happiness and all true advancement are found only in obedience to these laws.

Hygiene does not neglect the care of the sick. All true care of the sick recognizes and applies these same laws of nature in providing the needs of the sick and the removal of abnormal conditions. Disease results from disobedience to organic laws. Hygiene, as applied to the sick, is not the mere employment of diet, or of fasting; but it enters into all the causes of disease, seeking to remove these, and supplies all the needs of life in assisting the efforts of nature in restoring health. It provides a simple and healthful diet, carefully adapted to the assimilating powers of the body; it demands pure air and warmth; it provides rest or invigorating exercise as demanded, with other physical and normal Hygienic conditions.

A system of mind-body care that is valid both for a state of health and for one of illness must have as its most prominent feature appeal to the representatives of modern science, a principle capable of unifying all valid means and measures when caring for the organic body when well or sick. Such a principle will set each factor-element of a sound system of care in its proper place and thereby create a grand harmony and an easily understood system. It must be both universal and eternal in application; it can only rest upon one true principle; hence, it will be absolutely identical for each and every human being without regard to race, creed or color, without reference to climate, altitude, age, sex or occupation.

A system of care that must satisfy such enormous demands cannot be of an ephemeral nature nor something susceptible of merely local application. It must not be a fabricated system that some man or group of men have woven together out of disrelated elements, but must be constituted of every elemental factor of life itself. It cannot take aim at one special condition of the human body and mind, one special field of knowledge or organic experience. It cannot be partial to any one form of life or to anything that has to do with the support of life. It must leave open every conceivable opportunity for evolution.

It cannot be a mere fragment of truth; it must be truth itself. Otherwise it will not meet the demands made upon it. It will serve to divide rather than to unify the processes of caring for the well and the sick. It will result in discord between the means of care and the means of restitution, between the powers of life and the means with which to support these powers. If it is not truth itself, it will run counter to its professed principles and create biological antagonisms instead of biological harmonies.. Instead of becoming a basis for the attainment and maintenance of human health and sanity and of an enduring stability of structure and function, it will become a source of weakness and disease.

Hygiene is not the gift or invention of any man nor group of men nor of any succession of men, but the pristine way of life with which man emerged when he first came upon the earth.

The majestic strength of Hygiene lies in its naturalness, in its utter fitness to meet all the needs of the human organism. The wonders for which it is responsible are latent in its simplicity, in its harmony with the forces of life and in the absence of destructiveness in its relations to the body. The practices of Hygiene grow out of the plainest truths; so far as it is a system, it is founded in the nature of things. When we interfere with the natural systems, we soon discover that our own systems, which we try to substitute for the natural systems, are inadequate and result in wreckage.

Having thus shown that Hygiene legitimately takes cognizance of needs of health, we must seek to know the way which is right and live by it. We must seek to know the way which is wrong and shun it. Exact truth, simple nature, clear sunlight, pure air, fresh soft water, proper food, cleanliness, appropriate exercise, congenial temperature, rest and sleep, correct habits, obedience to the laws of life--are these too radical for the common understanding?

The view that natural living means living the uncultured and precarious life of the rudest tribes is both shortsighted and false. Whether civilized or not, man lives a natural life when he lives in accordance with the laws of his being. There is much in the lives of the rudest tribes that is very unnatural and unphysiological. We need to know not only the factor elements that constitute a system of Hygiene, but we must recognize and integrate all of the many and sometimes apparently contradictory facets of life, to the end that we may understand how to live in every particular. Violence is needed to hold asunder elements which are conjoined in nature, but we have much violence in civilization. It was Galen who classified food, water, sunshine, warmth, air, exercise, rest, wakefulness, the passions and affections of the mind, bowel movements, etc., as "non-naturals," and this false classification or unrecognized echoes of it, remains with us to this day. After all its high and beautiful imaginings, life is prosaic and eats bread--and this bread is a necessity.

In this connection, it is necessary that we keep in mind that Hygiene is not merely a collection of means of caring for the body, but also a group of correlated and integrated principles by which to apply these means. These principles are eternally antagonistic to the drugging system. When Trall declared that if Hygiene were adopted by medical men it would inevitably destroy medicine, he had in mind Hygiene as taught and practiced by Hygienists. He had no thought that physicians would endanger their system by endorsing washing the hands and scrubbing the teeth. Hygiene seeks to establish and understand the natural laws, or the regularity with which health and disease happen and to build on this sure basis of law. Lacking a rational, cohesive framework of valid principles, all the facts in the world fail to gain meaning. In fact, under such limitations, one may drown in facts. The limitations also tend to undue emphasis on subjective factors. Because it is based upon valid principles, Hygiene affirms its supremacy and its eventual acceptance by the peoples of the world. This will result in the eventual oblivion of the schools of healing.