In the book Qigong, The Art and Science of Chinese Energy Healing by Ken Cohen, the history of qigong starts with alchemists who were looking for an elixir of immortality. A fellow named Wei Bo-yang described an alchemical theory that became a cornerstone of qigong philosophy. His theory was that "things of a similar nature will cause changes in each other. This will not happen if there is dissimilarity."
Ken calls it the "theory of correspondance and affinity," and says that this theory influenced the development of modern qigong practices. Of course, homeopaths know the principle by another name - the doctrine of similars.