It is quite a prevalent idea in the community, that a man may be an ignoramus in regard to other subjects, and yet may have great skill in medicine. It is supposed that there is in the healing art a sort of mysterious tact or skill, innate in the man, and not acquired like other knowledge. It is this idea which gives such a reputation, for infallibility almost, to the natural bone-setter. We find here, also, the reason that intemperance in a physician so little impairs the confidence of his employers. It must be obvious that in no employment is a steady and clear state of mind more needed; and the obscurity of mind and recklessness, which intoxication, even when existing only in a slight degree, invariably produces, must unfit the physician for the proper performance of his duties. And yet how many sensible people, who would fear to trust an intemperate stage-driver or engineer, will unhesitatingly commit their health and life to the care of an intemperate physician, because they suppose that he has a peculiar skill, of which even intoxication cannot deprive him. His drunkenness seems to act as a dark background, making his skill appear the brighter by contrast.[34] In confirmation of this idea of the possession of innate skill, it is said that a man may be a fool on one subject, and yet may be a genius on another. A man may be, for instance, a great arithmetician, or a very ingenious mechanic, and may yet exhibit folly on most other subjects. This may be true in some few instances, but it is not at all common; and rare cases never can establish a general rule or principle. And besides, a genius in medicine, if he be a mere genius, in the popular sense of the term, makes but a poor practitioner. For true skill in the practice of medicine requires the possession of a wide range of talents, and among these sound judgment, or, (as it is familiarly called when used in reference to ordinary subjects,) common sense, is pre-eminent. This is a _sine qua non_ in the physician. The most brilliant talents cannot make one a good practitioner without this qualification. They may make him an interesting lecturer, or writer, and may give him a high reputation in the community. But his lack of this practical talent must render him unsuccessful in the treatment of disease, and the lectures which he may give will be deficient in practical instruction, and the books which he may write will add nothing to that storehouse of facts, which come only from observation, guided by a discriminating judgment, and plain common sense. He may construct beautiful theories, and explain and defend them with ingenuity, but he never can be a reliable source of instruction and information to his medical brethren.