The impression which is so common in regard to this subject is an erroneous one. The rules of intercourse which govern the medical profession abridge no man’s liberty. A strict adherence to them favors freedom of intercourse, by maintaining mutual confidence; while a disregard of them destroys this freedom, by engendering mutual distrust. The truly honorable physician is therefore always scrupulous in obeying them, while the dishonorable physician prefers a lax observance, because it furnishes him with occasional opportunities of obtaining by his manœuvres advantages over his medical brethren. I have thus noticed, as briefly as I could, some of the dishonorable practices which are common among physicians, impairing the harmony of their intercourse, and therefore limiting the usefulness of the profession. I have done so, principally because the community do not appreciate in any just degree the evil of these practices, and therefore those who are guilty of them generally escape with impunity, especially in the country, where there is no medical public opinion to control them, as there is in the cities and larger towns. It is well that the ‘tricks of the trade’ should be understood; and that the public should be able to discriminate, better than it now does, between those who are honorable practitioners, and those who are not. The differences, the jealousies, and the quarrels of medical men have become proverbial. ‘Who shall decide when doctors disagree,’ is often uttered as a reproach upon the profession, not only in regard to its opinions but its practices also. It is manifest to every one, that a jealous and quarrelsome spirit is more prevalent among physicians, than it is in the other professions. The reasons for this I will briefly notice. These reasons are to be found in the peculiar circumstances which attend the relations of physicians to each other, and the community. As the reader has already seen, the public have, for the most part at least, no _direct_ means of judging of the correctness of a physician’s practice, for the whole science of medicine is to them a mystery. He can commit the most gross and fatal errors, even while his patients and their friends may be reposing the most unlimited confidence in his skill and wisdom. His professional intercourse with them is indeed wholly a matter of confidence. The positions advanced by the lawyer can commonly be correctly appreciated by ordinary intelligence; the doctrines proclaimed by the clergyman it is the privilege and the duty of every man to examine by the light of the Bible; but the prescriptions of the physician must for the most part be taken upon trust. There is great room therefore for imposition; and the more, because with all this ignorance of medicine, most people are apt to think that they have no inconsiderable amount of knowledge on this subject.