I don't know the history, but homeopathy struck me as being based upon a misunderstanding of immunization response. If the first vaccines had been around, and whatsisname (who invented homeopathy) knew about them, it was... well... not horribly *unreasonable*, given the state of medical knowledge at the time.

(The story is that he ingested too much quinine and had symptoms not unlike malaria, and decided that this meant that "just enough" quinine made the body fight against malarial symptoms.)