When plants could cure, kill… or shock

FOR many centuries, the theory held that if some part of a plant resembled a human organ, then that plant could be used to treat the organ it resembled. At the heart of folk remedy and herbalism, this notion was nurtured throughout the classical world by respected medical scribes as far distant as Dioscorides (c40-90BC, Greek physician and botanist) and Pliny the Elder (cAD 23-79, Roman naturalist, author of Naturalis Historia, the role model for all encyclopedias). It gained theological credence in medieval times, and for a while was central to Western culture.

The doctrine of signatures

It was known as the Doctrine of Signatures. The 16th century Swiss physician Paracelsus declared that ‘Nature marks each growth according to its curative benefit’, and German religious mystic Jacob Boehme travelled a similar course with (, 1621), which is said to have influenced Isaac Newton