Christian Friedrich Samuel Hahnemann (10th April 1755 - 2nd July 1843) was a physician who founded homoeopathic medicine. Hahnemann is also credited with introducing the practice of quarantine while employed by the Duke of Anhalt-Köthen. A monument in Washington D.C. commemorates his life and works. Hahnemann's notable works include:
- The Organon of the Healing Art (1810) explains the theory of homeopathic medicine. Hahnemann published the 5th edition in 1833; an unfinished 6th edition was discovered after Hahnemann's death but not published until 1921.
- Materia Medica Pura is a compilation of homoeopathic proving reports, published in six volumes during the 1820s (vol. VI in 1827). Revised editions of volumes I and II were published in 1830 and 1833, respectively.
- Chronic Diseases (1828) is his account of the root and cure of chronic disease together with a compilation of homoeopathic proving reports, published in five volumes during the 1830s.
Born Christian Friedrich Samuel Hahnemann in Meissen, Saxony on April 10, 1755, Hahnemann showed early proficiency at languages, and by the age of twenty had mastered English, French, Italian, Greek and Latin, and was making a living as a translator and teacher of languages. He later became proficient in Arabic, Syriac, Chaldaic and Hebrew. Hahnemann studied medicine at Leipzig and Vienna, and received his doctor of medicine degree at the University of Erlangen on 10 August 1779, qualifying with honors with a thesis on the treatment of cramps. He began practicing as a doctor in 1781, and shortly after, married Johanna Henriette Kuchler; they had eleven children.
Through his practice, Hahnemann concluded rightly that the Galenic medicine of his day did as much harm as good. Bloodletting, purging, and enemas were all in common use, and it would take more than fifty years before Ignaz Semmelweis’s proposal that hand-washing significantly reduced mortality was finally accepted, with the advent of the germ theory of disease: "My sense of duty would not easily allow me to treat the unknown pathological state of my suffering brethren with these unknown medicines. The thought of becoming in this way a murderer or malefactor towards the life of my fellow human beings was most terrible to me, so terrible and disturbing that I wholly gave up my practice in the first years of my married life and occupied myself solely with chemistry and writing."
After giving up his practice, Hahnemann earned his living mainly as a writer and translator. While translating William Cullen's A Treatise on the Materia Medica, Hahnemann encountered the claim that Cinchona, the bark of a Peruvian tree, was effective in treating malaria because of its astringency. Hahnemann realised that other astringent substances are not effective against malaria and began to research cinchona's effect on the human organism very directly: by self-application. He discovered that the drug evoked malaria-like symptoms in himself, and concluded that it would do so in any healthy individual. This led him to postulate a healing principle: "that which can produce a set of symptoms in a healthy individual, can treat a sick individual who is manifesting a similar set of symptoms." This principle, like cures like, became the first of a new medicinal approach that he called homeopathy.
Hahnemann began testing substances for their effects on healthy individuals, and in particular tried to find lower doses at which they might have healing effects without serious adverse effects. He concluded that even very highly diluted substances, when done according to his technique of succussion (systematic mixing through vigorous shaking) and potentization, were still effective. Today we recognise that these highly diluted substances in fact can contain no trace of the original ingredients, and that any effects they appear to have are likely to be placebo effects - but in Hahnemann's time there was no concept of a placebo effect, and no understanding that there was any effective limit to how far substances might be meaningfully diluted.
Hahnemann began practicing medicine again using his new technique, which soon attracted other doctors. He first published an article about the homeopathic approach to medicine in a German medical journal in 1796; in 1810, he wrote his Organon of the Medical Art, the first systematic treatise on the subject. Hahnemann continued practicing medicine, researching new medicines, writing and lecturing to the end of his life. He died in Paris in 1843, aged 88 years, and is entombed in a mausoleum at Paris's Père Lachaise cemetery.
- The highest ideal of cure is the speedy, gentle, and enduring restoration of health by the most trustworthy and least harmful way (Samuel Hahnemann)
In his day, Hahnemann acquired a considerable reputation as a practitioner of medicine, as a scientist in pharmacology, and for promoting the importance of good hygiene. Christoph Hufeland (1762 – 1836), the most eminent practical physician of his time in Germany, was, according to Ameke (1885), a close friend of Hahnemann, who "never lost respect for Hahnemann's genius and services to medicine." 
As a translator, Hahnemann was widely regarded as a writer who "improved and perfected" any text translation he undertook. Many honours and accomplishments in chemistry and pharmacy preceded his discovery of homeopathy, what Ameke calls "his pre-homeopathic labours." For example, "in 1788, Hahnemann discovered the solubility of metallic sulphates in boiling nitric acid."
While homeopathy is no longer taken seriously by all but a very few scientists and conventional physicians, Hahnemann is still remembered for his considerable contributions to public health, in particular for promoting awareness of the importance of hygiene and clean water, and for his early recognition of the deficiencies of the "heroic medicine" of his day.
Thomas Lindsley Bradford, Life and Letters of Dr Samuel Hahnemann, Philadelphia: Boericke & Tafel, 1895 
- Wilhelm Ameke, History of Homœopathy, with an appendix on the present state of University medicine, translated by AE Drysdale, ed RE Dudgeon, London: E. Gould & Son, 1885.