Health and disease are physical conditions upon which pleasure and pain, success and failure, depend. Every individual gain increases public gain. Upon the health of its people is based the prosperity of a nation; by it every value is increased, every joy enhanced. Life is incomplete without the enjoyment of healthy organs and faculties, for these give rise to the delightful sensations of existence. Health is essential to the accomplishment of every purpose; while sickness thwarts the best intentions and loftiest aims. We are continually deciding upon those conditions which are either the source of joy and happiness or which occasion pain and disease. Prudence requires that we should meet the foes and obviate the dangers which threaten us, by turning all our philosophy, science, and art, into practical common sense.

The profession of medicine is no sinecure; its labors are constant, its toils unremitting, its cares unceasing. The physician is expected to meet the grim monster, "break the jaws of death, and pluck the spoil out of his teeth." His ear is ever attentive to entreaty, and within his faithful breast are concealed the disclosures of the suffering. Success may elate him, as conquest flushes the victor. Honors are lavished upon the brave soldiers who, in the struggle with the foe, have covered themselves with glory, and returned victorious from the field of battle; but how much more brilliant is the achievement of those who overwhelm disease, that common enemy of mankind, whose victims are numbered by millions! Is it meritorious in the physician to modestly veil his discoveries, regardless of their importance? If he have light, why hide it from the world? Truth should be made as universal and health-giving as sunlight. We say, give light to all who are in darkness, and a remedy to the afflicted everywhere.

We, as a people, are becoming idle, living in luxury and ease, and in the gratification of artificial wants. Some indulge in the use of food rendered unwholesome by bad cookery, and think more of gratifying a morbid appetite than of supplying the body with proper nourishment. Others devote unnecessary attention to the display of dress and a genteel figure, yielding themselves completely to the sway of fashion. Such intemperance in diet and dress manifests itself in the general appearance of the unfortunate transgressor, and exposes his folly to the world, with little less precision than certain vices signify their presence by a tobacco-tainted breath, beer-bloated body, rum-emblazoned nose, and kindred manifestations. They coddle themselves instead of practicing self-denial, and appear to think that the chief end of life is gratification, rather than useful endeavor.

I purpose to express myself candidly and earnestly on all topics relating to health, and appeal to the common sense of the reader for justification. Although it is my aim to simplify the work, and render it a practical common-sense guide to the farmer, mechanic, mariner, and day-laborer, yet I trust that it may not prove less acceptable to the scholar, in its discussion of the problems of Life. Not only does the method adopted in this volume of treating of the Functions of the Brain and Nervous System present many new suggestions, in its application to hygiene, the management of disease, generation and the development and improvement of man, but the conclusions correspond with the results of the latest investigations of the world's most distinguished savants. My object is to inculcate the facts of science rather than the theories of philosophy.

Unto us are committed important health trusts, which we hold, not merely in our own behalf, but for the benefit of others. If we discharge the obligations of our trusteeship, we shall enjoy present strength, usefulness, and length of days; but if we fail in their performance, then inefficiency, incapacity, and sickness, will follow, the sequel of which is pain and death. Let us, then, prove worthy of this generous commission, that we may enjoy the sweetest of all pleasures, the delicious fruitage of honest toil and faithful obedience.