Walnuts for Brains

The internet is a revelation. Where else could one encounter abundant evidence that, despite the Enlightenment and expensive educational systems, ignorance is not merely pervasive, but lauded?

A case in point—New Age embrace of the long-discredited Doctrine of Signatures.

The Doctrine of Signatures dates from the time of Dioscurides (c. 40 – 90 AD) and Galen (AD 129 – c. 200/c. 216). According to proponents of the doctrine, herbalists could use the vague resemblance between the appearance of herbs and body parts to treat ailments attributed, most often wrongly, to those organs. The later Christian theological justification was that God would have wanted to direct men to useful plants.

Examples:

Eyebright, used for eye infections

Hedge woundwort, thought to have antiseptic qualities

Liverwort, either Marchantiophyta or Hepatica - used to treat the liver

Lungwort – Lobelia pulmonaria (and others) - used for pulmonary infections

Spleenwort, Asplenium - used to treat the spleen

Toothwort, Dentaria - used for tooth ailments

In its innocuous form, this belief is embodied in the naming—both popular and Linnaean—of plants.

Unfortunately, because the doctrine has no basis in fact, the practice has proved invariably ineffective, often harmful, and too often fatal.

Examples (discussed in the playlist below):

Hyoscyamus niger, black henbane, for toothache

Aristolochia clematitis, birthwort, in midwifery
Mandragora officinarum, mandrake, as aphrodisiac

Links:

Fantastically Wrong: The Strange History of Using Organ-Shaped Plants to Treat Disease .

Doctrine of Signatures .

Magical Thinking .
Naturalistic Fallacy .

How to protect yourself from harm in Anglo-Saxon England .
The power of plants (and an Anglo-Saxon cold remedy) .