Doctrine of Signatures

The Doctrine of Signatures is a very old notion which predates homeopathy and was already mentioned in the writings of the Swiss physician Paracelsus von Hohenheim (1493-1541). It proposes the idea that God gave everything in nature its unique healing powers and left a clue for us to discover in the appearance of each plant or substance. For example, the dark lines on the petals of Digitalis purpurea are reminiscent of blood vessels. Indeed, Digitalis is a well-known allopathic drug for heart problems and also has an affinity for this organ in its homeopathic preparation. Similarly, the yellow juice of Chelidonium majus reminds one of the yellowish complexion typical of patients with liver problems. Chelidonium is known for its affinity to the liver.
As a scientific system, there is no basis for confirming these associations that folk medicine has given us. What they do provide us with is a very good basis for a mnemonic system. In studying materia medica, you can take advantage of Euphrasia's pupil-like markings as a way to remember that Eyebright is a major remedy for the eyes.