Homeopathy (also spelled homœopathy or homoeopathy), from the Greek words homoios (similar) and pathos (suffering), is a system of medicine, notable for its practice of prescribing water-based solutions that do not contain chemically active ingredients. The theory of homeopathy was developed by the Saxon physician Samuel Hahnemann (1755–1843) and first published in 1796. It has a wide and growing popularity in areas where it is practiced today, but the way homeopathy medicines work and many of the fundamental principles of homeopathy are still not well understood.