Samuel Christian Friedrich Hahnemann, the founder of the homoeopathic system of medicine, born in Meissen, Saxony, April 10, 1755, died in Paris, July 2, 1843. He was educated at the high school of his native town, and at the age of 20 went to Leipsic to study medicine. Here he devoted his leisure to teaching languages, and to translating foreign medical authors into German, and was accustomed to sleep only every other night, a habit he persevered in for several years. In 1777 he went to Vienna, where he came under the notice of Quarin, physician to Joseph II. and chief physician to the hospital of the Leopoldstadt, who intrusted him with the care of one of the hospital wards, and subsequently recommended him to Baron von Bruckenthal, the governor of Transylvania, in whose family at Hermann-stadt he remained as librarian and physician for nearly two years. In August, 1779, he took his degree of M. D. at Erlangen. After a brief residence in Hettstadt and Dessau, where he studied chemistry and mineralogy, and at Gommern near Magdeburg, where in 1785 he was married, he settled in 1787 in Dresden. Here he was rapidly acquiring reputation as a physician and writer on medical science, when a distrust of the received system of therapeutics caused him to pause in his labors.

In place of facts and laws, he complained that he found only hypotheses and theories. Finding that he could no longer conscientiously practise his profession, he returned in 1789 to Leipsic, where he resumed his chemical studies, and endeavored to support his family by translating English and French medical authors. At first he was obliged to struggle with poverty, and his children experiencing severe attacks of illness, he could only prescribe for them according to a system in which he had ceased to place confidence. This stimulated his desire to establish a new system of therapeutics. In 1790, while engaged upon a translation of Cullen's "Materia Medica," he was struck with the contradictory properties ascribed to Peruvian bark, and the various explanations given of its operation in intermittent fever. He resolved to try upon himself the effects of the medicine, and, after several powerful doses, discovered symptoms analogous to those of intermittent fever. The fact that a drug had produced upon a man in health the very symptoms which it was required to cure in a sick man immediately suggested to him the law, Similia similibus curantur ("Like cures like"), which is the groundwork of the homoeopathic system.

He determined to test the principle fully before announcing it to the world, and experimented upon himself with a variety of drugs. Similar results having been obtained in every instance, and also in experiments tried upon others, he applied the new law to the treatment of the patients in the insane asylum at Georgenthal near Gotha, over which the duke of Saxe-Gotha bad appointed him, with complete success. From Georgenthat he proceeded to Pyrmont, Brunswick, and Konigslutter, effecting in each place remarkable cures. In 1796, in a paper published in Hufeland's Journal der praktischen Heilkunde, he made his first public exposition of the similia similibus principle, which, if not its discoverer, he was the first to declare to be the leading principle in therapeutics. His suggestions were received with indifference or ridicule, and during the next 15 years he was the object of ceaseless attacks from those whose interests were opposed to the innovations he sought to introduce into medical practice.

During this period he published several works, all treating of the new theory; among which was Fragmenta de Viribus Medicamentorum Positivis site Obriis in Corpore Sano (2 vols., Leipsic, 1805). But in his Organon der ra-tionellen Heilkunde (Dresden, 1810) homoeopathy first received its distinctive name, and was first reduced to a system and methodically illustrated. This work created much sensation in Germany, and a bitter warfare was waged for upward of 12 years between the old and new schools of therapeutics. About this time he fixed his residence in Leipsic, where he entered upon an extensive practice, and gathered about him many friends and disciples. During the prevalence of a malignant form of typhus in 1813, caused by the recent presence of the allied and French armies, the patients became so numerous that it was necessary to divide them among the physicians of the city. Of the 73 allotted to Hahnemann, and treated on the homoeopathic method, all recovered except one old man. But this only increased the enmity of his opponents, and an old law was revived which prohibited a physician from dispensing his own medicines, a practice Hahnemann had always followed, and was unwilling to relinquish.

He therefore in 1820 removed to Kothen, where for a time he encountered the same hostility which had driven him from Leipsic. But the homoeopathic system was meanwhile making its way silently over Europe, and patients repaired from all sides to receive the advice of its founder. The importance which the petty town of Kothen thus acquired soon caused a reaction in his favor, and when, upon his marriage for a second time in 1835 with Mlle, d'Hervilly, a young French woman, he took his departure, it was deemed necessary to go secretly by night for fear the populace might insist upon detaining him. Repairing with his wife to Paris, he resided there in the active practice of his profession until his death. A statue of Hahnemann was erected in Leipsic in 1851 by the homoeopathic physicians of Germany, and another in Berlin in 1855. Besides those already mentioned, his principal works are: Reine Arzneimittellehre (6 vols., Dresden, 1811-'20; 3d ed., 1830-'33); Die chronischen Krankheiten (4 vols., Dresden, 1828-'30; 2d ed., 1835-'9); and Heilung der asiatischen Cholera (Nuremberg, 1831). A collection of his minor works has been published (2 vols., Dresden, 1829-34). Several of his works have been translated into English and other languages. (See Homoeopathy.)