Mercury was known to the early Greek and Roman physicians, who regarded it as a dangerous poison. They, however, used it externally in curing the _itch_, and John de Vigo employed it to cure the plague. Paracelsus used it internally first for _lues venerea_, which appeared in Naples the year of his birth, though doubtless that disease reached far back, even into the camp of Israel. The heroic doses of Paracelsus either destroyed the disease at once, _or the patient_. Paracelsus proclaimed to the world that there was no further need of the _Materia Medica_, especially the writings of Galen, and burned them in public; his "Elixir Vitæ" would cure all diseases. But in spite of his wonderful knowledge and his life-saving elixir, he died of the diseases he professed to cure, at the early age of forty-eight, while Galen lived to the age of seventy. So much for the "father of quacks." For nearly four centuries mercury has been exhibited in the _Materia Medica_ to a greater extent than any other remedy. Doubtless it possesses great medicinal virtues, but its abuse--the "heroic doses" used by the ignorant and brainless quacks, both graduates of some medical college, and _soi-disant_ physicians--has made its name a terror to the people and a reproach to the profession. To assail it is to tread on dangerous ground; to invade the "rights" of a numerous host of worshippers; to uncover an ulcer, whose rottenness, though smelling to heaven, is protracted for the pecuniary advantage of the prescriber. Eminent physicians in every age since its introduction, and in every enlightened country, have protested against its abuse; yea, even its use! They have called its users "_quacks_," the most contemptible epithet ever introduced into medical nomenclature,--the "_Samson_" of the profession, because through the instrumentality of an ass and his adherents, "it has slain its thousands." I need not quote those distinguished practitioners who have recorded their testimony against its general and indiscriminate use. Their name is legion, and every well-informed physician is aware of the fact. Do not "well-informed physicians" prescribe calomel? Certainly; but cautiously, and often under protest. It is recorded of Sir Astley Cooper that he made serious objections to its free use in the wards of the Borough Hospitals, and forthwith the "smaller fry" made such a breeze about his ears that he seemed called upon to defend, and even palliate, his offence. Dr. Macilwain says that Sir Astley is reported to have said in reply to those who demurred,-- "Why, gentlemen, was it likely that I should say anything unkind towards those gentlemen? Is not Mr. Green (surgeon of St. Thomas) my godson, Mr. Tusell my nephew, Mr. Travers my apprentice (surgeon of St. Thomas), Mr. Key and Mr. Cooper (surgeons of Guy's Hospital) my nephews?"