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Provings are carried out in a number of ways, depending on who is conducting the trial. This usually involves following Samuel Hahnemann’s protocol but may extend to a person taking the remedy and meditating on the effects. Most authoritative provings are done following a strict method, laid down in Jeremy Sherr's book entitled The Dynamics and Methodology of Homoeopathic Provings, published by Dynamis Books. See especially pages 45-55.
A proving typically involves about 20 volunteers taking six doses of the remedy over two days. If symptoms occur then no further doses are taken. During this time, and for some time after, each prover keeps a diary recording all mental, physical and emotional symptoms that are experienced during the proving. At the end of the proving period the master prover will collate the symptoms from the diaries, excluding those symptoms which have been demonstrated to be symptoms that the prover experienced, before the proving commenced. This part of the process can be quite time comsuming. Finally the proving is published in its entirety. In order to give a full remedy picture it is normal for the provers to take the remedy at a range of potencies.
A more recent development involves having some of the participants in a trial take a placebo. The symptoms recorded by these provers are compared to the symptoms recorded by the other provers in order to aid the process of deciding which symptoms are caused by the remedy. Some such 'placebo-controlled' provings may not qualify as either randomized controlled trial, since the participants are not randomized and the master prover is routinely aware of who is on placebo. In most modern, well conducted provings even the master prover is not aware of who is on placebo, and they therefore may legitimately be regarded as double blind.
A curiosity is that in some instances, the provers on placebo have been observed to produce symptoms similar to those who are taking the remedy. Homeopaths attribute this observation to field effects ('energetic resonance'). However, in strict scientific terms this would indicate rather that there is probably no difference between the treatment and the placebo.
Hahneman and Provings
Homepathic remedies are found by 'provings', in which volunteers are given substances, the effects of which are recorded as a 'Drug Picture'. Of his first proving, Hahnemann said: "with this first trial broke upon me the dawn that has since brightened into the most brilliant day of the medical art; that it is only in virtue of their power to make the healthy human being ill that medicines can cure morbid states, and indeed, only such morbid states are composed of symptoms which the drug to be selected for them can itself produce in similarity on the healthy." At first, Hahnemann tested substances such as antimony and rhubarb, and poisons like arsenic, mercury and Belladonna, that were used as medicines. He recorded his first provings of 27 remedies in the Fragmenta de viribus in 1805; his later Materia Medica Pura contained 65 remedies.
James Tyler Kent (1849-1921)  was almost as important as Hahnemann to the development of homeopathy; his Lectures on Homoeopathic Materia Medica (1905) listed 217 remedies. Kent emphasized the metaphysical and clinical aspects of Hahnemann's teachings; the core doctrines of miasm and vital force, and the importance of spiritual factors as the cause of disease ("for it goes to the very primitive wrong of the human race, the very first sickness of the human race that is the spiritual sickness... which in turn laid the foundation for other diseases" ). Modern medicine recognizes that bacteria and viruses as the causes of many diseases, but for Kent "The microbe is not the cause of disease. We should not be carried away by these idle Allopathic dreams and vain imaginations but should correct the Vital Force". In the UK, his ideas became homeopathic orthodoxy by the end of the First World War, and some homeopaths still regard microbes as effects, not causes, of disease. 
Today, homeopaths use about 3000 different remedies from animal, plant, mineral, and synthetic substances, including 'Natrum muriaticum' (sodium chloride or table salt), 'Oscillococcinum' (a 200C product made from duck heart and liver that is prescribed for colds and flu-like symptoms) 'Roadrunner' (Geococcyx californianus)  and 'Arnica' . Other 'isopathic' remedies involve diluting the agent or product of the disease; for example, Rabies nosode is made from the saliva of a rabid dog. Some homeopaths use more esoteric substances, known as 'imponderables' because they originate from electromagnetic energy 'captured' by alcohol or lactose ('X-ray', 'Sol' (sunlight), 'Positronium', and http://homeoint.org/clarke/e/elect.htm 'Electricitas'](electricity), or with a telescope ('Polaris'). Recent ventures into more esoteric remedies include 'Tempesta' (thunderstorm), and 'Berlin wall'.
The law of similars is not a scientific law, and a failure to cure can always be attributed to the wrong choice of remedy; in Kent's words, "I have often heard physicians tell me that it was due to suggestion that my medicines acted so well; but my answer to this is, that I suggest just as strongly with my wrong remedy as with the right one, and my patients improve only when they have received the similar or correct remedy". There are many ways to find the most-similar remedy (the simillimum), and homeopaths sometimes disagree. This is partly due to the complexity of the 'totality of symptoms' concept; homeopaths decide, from their knowledge and experience, which symptoms are the most characteristic: the Drug Picture in the Materia Medica is always more comprehensive than the symptoms of any individual. Other ways are through medical dowsing or other psychic powers, but these are not accepted by most homeopaths. 
- Campbell A Kentian Homeopathy, Chapter 8 of Homeopathy in Perspective ; Morrell P Kent's influence on British homeopathy
- Kent JT (1926) 'New Remedies, Lesser Writings and Aphorisms and Precepts', quoted in Treuherz F (1984) Origins of Kent's homeopathy J Amer Inst Homeo 77:130-49
- Diagnostic dowsing machines; "Medical dowsing"
- Homeopathy Drug Proving - Information about homeopathic drug provings and a collection of old and new provings.
- World Wide Proving Index - Open access database of recent provings
- Sherr J The Dynamics and Methodology of Homoeopathic Provings, published by Dynamis Books
- Hahnemann C F S Organon of Medicine, translated by Dudgeon R E & Boericke W, 5th & 6th Editions