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.”]

But it is especially the prerogative, I had almost said privilege, of educated and domesticated beings, from man down to the potato, serving to teach them, and such as train them, the laws of life, and to get rid of those who will not mind or cannot be kept subject to these laws.

Disease, being always an effect, is always in exact proportion to the sum of its causes, as much in the case of Spigelius, who dies of a scratch, as in that of the man who recovers after an iron bar has been shot through his brain.  The one prevalent failing of the medical art is to neglect the causes and quarrel with the effect.