But first, there are a number of terms which we are in the habit of using in a vague though not unintelligible way, and which it is as well now to define. These terms are the tools with which we are to work, and the first thing is to sharpen them. It is nothing to us that they have been sharpened a thousand times before; they always get dull in the using, and every new workman has a right to carry them to the grindstone and sharpen them to suit himself.
Nature, in medical language, as opposed to Art, means trust in the reactions of the living system against ordinary normal impressions.
Art, in the same language, as opposed to Nature, means an intentional resort to extraordinary abnormal impressions for the relief of disease.
The reaction of the living system is the essence of both. Food is nothing, if there is no digestive act to respond to it. We cannot raise a blister on a dead man, or hope that a carminative forced between his lips will produce its ordinary happy effect.
Disease, dis-ease,—disturbed quiet, uncomfortableness,—means imperfect or abnormal reaction of the living system, and its more or less permanent results.
Food, in its largest sense, is whatever helps to build up the normal structures, or to maintain their natural actions.
Medicine, in distinction from food, is every unnatural or noxious agent applied for the relief of disease.
Physic means properly the Natural art, and Physician is only the Greek synonyme of Naturalist.
With these few explanations I proceed to unfold the propositions I have mentioned.
Disease and death, if we may judge by the records of creation, are inherently and essentially necessary in the present order of things. A perfect intelligence, trained by a perfect education, could do no more than keep the laws of the physical and spiritual universe. An imperfect intelligence, imperfectly taught,—and this is the condition of our finite humanity,—will certainly fail to keep all these laws perfectly. Disease is one of the penalties of one of the forms of such failure. It is prefigured in the perturbations of the planets, in the disintegration of the elemental masses; it has left its traces in the fossil organisms of extinct creations. [Professor Agassiz has kindly handed me the following note: “There are abnormal structures in animals of all ages anterior to the creation of mankind. Malformed specimens of Crinoids are known from the Triassic and Jurassic deposits. Malformed and diseased bones of tertiary mammalia have been collected in the caverns of Gailenreuth with traces of healing.”]