Homeopathy is recognised by the World Health Organization as the second largest therapeutic system in the world. Established 200 years ago by German physician Samuel Hahneman, homeopathy is a complementary medicine that is based on the principle of similars - like cures like - which means that a substance that can cause certain symptoms in a healthy person can cure similar symptoms in an unhealthy person. Homeopathy aims to aid and stimulate the body's own defense and immune processes. Homeopathic medicines are derived from a variety of plants, animal materials and minerals.