your immediate acceptance, nor yet for your
hasty rejection, but for your calm consideration.

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 creati