Homeopathy, from Greek homoeo (meaning similar) and pathos (meaning suffering) is a system of medicine based on treating like with like. The same principle is widespread in mainstream medicine, the most notable examples being antidotes and vaccines. However, Homeopathy takes this premise a step further: if my symptoms produce an effect on me similar to a tarantula's bite, then tarantula venom would be my homeopathic treatment, even though I've not actually been bitten by a tarantula.

The theory that like can be treated with like can be traced back as far Hypocrites (468 -377 BC), but it wasn't until the work of Samuel Hahnemann (1755-1843) that the theory developed into a usable practice.

Hahneman's provings consisted in giving doses of various substances to both himself and his healthy volunteers, and noting the effects in detail. For safety reasons, the substances taken were very dilute, and it is here that Hahnemann chanced upon one of the more puzzling aspects of Homeopathy. The more dilute a homeopathic medicine is, the more effective it is in treating illness.

Hahneman's work was continued by James Tyler Kent in 1877-78. Kent's interest in Homoeopathic medicine was prompted by his wife's serious illness, which failed to respond to any other form of medicine available at the time.