Medical theorists have arranged diseases into different orders, classes, and kinds, according to their symptoms, giving to each a different name, and recommending for each a different mode of treatment. This course has involved the practice of medicine in darkness, perplexity, and doubt. No physician can decide for a certainty, what organ is primarily affected, or what name to give the disease. He must therefore do nothing until the symptoms are so far developed as to enable him to give it a name, or lift his club and strike at random.

Said Dr. Abercrombie, a distinguished physician, " I am under the necessity of acknowledging, that since medicine was first cultivated as a science, a leading object of attention has ever been to ascertain the characters and symptoms by which particular internal diseases are indicated, and by which they are distinguished from other diseases, which resemble them. But, with the accumulated experience of ages bearing upon this important subject, our extended observation has only served to convince us how deficient we are in this department, and how often, in the first step of our progress, we are left to conjecture. A writer of high eminence, Morgagni, has even hazarded the assertion that persons are the most confident in regard to the characters of disease, whose knowledge is most limited, and that more extended observation generally leads to doubt.

"Disease is nothing more nor less than a deviation from a state of health, consisting in, or depending on, an obstruction or diminution of the vital energies; exhibiting different symptoms according to the extent of the deviation, the importance of the organ affected, or peculiar state of the person coming under influences capable of producing a state of disease.

He who does not enjoy perfect health is more or less under the influence of disease; the cause of which being continued, disease progresses, acting on different organs, deranging different functions, and exhibiting new symptoms, until the powers of nature yield, and death is the result.

A disease is either general or local, functional or organic. It is general, when the whole system is affected; and local, when it is confined to a particular part. A disease is functional, when an organ is laboring under some derangement; and organic, when there is an alteration in the structure of the organ.