Doctrine of signatures
The doctrine of signatures was an important aspect of folk medicine from the Middle Ages until the early modern period. Often associated with the work of herbalists and wise women, it drew upon the belief that natural objects that looked like a part of the body could cure diseases that would arise there. Folk healers in Christian and Muslim countries claimed that God, or Allah, deliberately made plants resemble the parts of the body they could cure. For example, eyebright, a plant whose flower looks like bright blue eyes, was used to treat eye diseases. The use of eyebright for this purpose was still common in the 1700s. Today the idea of ‘like cures like’ lies at the heart of modern homeopathy.
This belief became known as the ‘doctrine of signatures’ after the appearance of a book by the German mystic Jakob Boehme called The Signature of All Things (1621). The Swiss physician Paracelsus, an important advocate of the doctrine of signatures, stated that ‘Nature marks each growth… according to its curative benefit.’ Similarly, the English botanist William Cole (1626-62) believed that ‘the mercy of God... maketh… Herbes for the use of men, and hath… given them particular Signatures, whereby a man may read… the use of them.’
Techniques and Technologies:
J Boehme, Signatura Rerum, or The Signature of All Things, edition translated and prefaced by J Ellistone, (London: Gyles Calvert, 1651)
W Cole, Adam in Eden or Nature's Paradise (London: J Streater for Nathanial Brooke, 1657)
L I Conrad, M Neve, V Nutton and R Porter, The Western Medical Tradition, 800 BC – 1800 AD (Cambridge: Cambridge University Press, 1995)
R Porter, The Greatest Benefit to Mankind: A Medical History of Humanity from Antiquity to the Present (London: HarperCollins, 1997)