The founder of Homoeopathy was Dr. Samuel Hahnemann (1755-1843). Based on his observations, he formulated the so-called PRINCIPLE OF SIMILARITY, which states that a given substance can cure in a diseased person the symptoms that it produces or causes in a healthy person. Homoeopathy is a well-described, scientifically based system of approaching health and disease. "Scientific" because the insights are based on reproducible experiments. "Well-described" because from these observations a number of precise basic fundamental rules became evident, first among them the "similarity principle."
Hahnemann published his ideas and experiences in a book called the Organon. The first edition appeared in 1810 and he wrote the last edition (which appeared posthumously) in 1842.