Homoeopathy was developed by Dr Samuel Hahnemann (1755-1843) starting with his recognition of the Law of Simila as a general therapeutic law. Although people like Hippocrates and Paracelsus (born around 1493), had proposed & used similar ideas in their times, it was Dr. Hahnemann who first recognised & applied this therapeutic principle as a general law.
In the 18th century, the medical science was still very unscientific. The knowledge about human body, diseases and the modalities of treatment were poor and vague. Methods like blood-letting, leeching, purging were the common treatments for most ailments. Practically the whole of the 18th century in Europe was marked by a plethora of theories and hypothesis concerning the nature of disease and its causation. Consequently methods of therapeutic practice were as numerous and diverse as the theories propounded. The uncertainty and lack of any fixed principle of healing disappointed Dr. Hahnemann.
So Dr. Hahnemann relinquished his medical practice & devoted himself to the translation of great medical classics of his time. In 1790, when Dr. Hahnemann was engaged in translating William Cullen's (a Scottish physician) materia medica from English to German, his attention was arrested by the remark of the author that cinchona bark cured malaria because of its bitterness & tonic effects on stomach. This explanation appeared unsatisfactory to him. In his youth he had travelled in a particular area of Hungary where Marsh Fever or Malaria had been rife. He had used the herb, Cinchina Bark, but his experience did not support the conclusion of Cullen's paper. He decided to carry out some experiments of his own.
He took a dose of the herb himself and he found that he developed symptoms very much like Marsh Fever. He realised that the power to cure the disease could cause the symptoms of the disease. He tried it on his family, friends and volunteers and they all developed the same sort of symptoms. He experimented with this one drug on many people and the majority of them told the same story. In 1796, after 6 years of Dr. Hahnemann's first experiment, he published an article in Hufeland's Journal volume-II, parts 3 & 4, pages 391-439 & 465-561. "An essay on a new principle for ascertaining the curative powers of drugs & some examinations of the previous principle."