Memory theatre

In days of yore, one of the ways of memorising complex collections of information was via a technique known as "Memory Theatre". This is similar to the contemporary technique of hanging information on a system where bizarre imagery is used to help one recall less memorable information. For instance, the cabbalistic tree of life is sometimes used in this way.

Astrological imagery is one way of doing this, and another is the doctrine of signatures. I want to start from an agnostic position concerning the nature of the connections made between the features on which one focuses with these methods.

The doctrine of signatures is the belief that there is a link between perceived features of a plant and its medical uses. For instance, hawthorn berries (Crataegus oxyacanthoides (fructus)) are used for their cardiac action and superficially resemble the heart, dandelion root (Taraxacum officinale (radix)) is employed as a liver tonic and has yellow flowers, reminiscent of jaundice, and sage (Salvia officinalis) is hairy and has a traditional use to prevent alopecia. This is quite an ad hoc system. Less arbitrary is the system whereby links are made between the planets in astrological terms and particular plant species. This tends to operate as follows:

Mercury: Plants with finely divided parts, linked to the nervous system or connected to communication. Example: dill (Anethum graveolens).
Venus: Plants with prominent female reproductive parts or concerned with visible aspects of the body. Examples: gooseberry, Ribes uva-crispa and the dog rose, Rosa canina.
Mars: Plants perceived as defending themselves, with mechanical or chemical weapons. Examples: Urtica dioica (nettle), Capsicum minimum (Cayenne pepper).
Jupiter: Expansive herbs, such as Quercus robur (oak),
Saturn: Plants that are poisonous or have prominent rings. Example: Artemisia absinthium (wormwood).
Sun: Plants with parts which resemble the Sun or are warming. Example: Calendula officinalis (French marigold).
Moon: Watery herbs, either high in water content or associated with water. Examples: Salix nigra (black willow), Fucus vesiculosus (bladder wrack).

All of these associations hearken back to astrological categorisations of the world, but they do not have to be taken literally. When I learnt the cranial nerves, I used the mnemonic "On Old Olympus Topmost Top, A Finn And German Viewed A Hop." The fact that I used that sequence does not mean there is any necessary connection between Germany and the glossopharyngeal nerve, but it does help me remember that CN IX supplies the tongue and the pharynx. Similarly, there are associations between features of herbs and their reputed actions and the picturesque realms of the doctrine of signatures and astrology. Sometimes there could be other associations with the herbs: for instance, gooseberry bushes have thorns, and so could be considered to be herbs of Mars rather than Venus, and in fact Nicholas Culpeper comments on this, but an association can be created in this way.

Today, it is possible to look at a herb, say Valeriana officinalis, and make an association between isovalerianic acid and the major neurotransmitter of the parasympathetic nervous system gamma-aminobutyric acid (GABA), and so it can be seen as a sedative. This is a story I tell myself to connect the sedative action of Valeriana to its constituents. It is a proposition which has not, so far as I know, been falsified, and therefore through Karl Popper's philosophy of science, it is falsifiable or can be corroborated. Empirical scientific propositions are not yet falsified: they are not true in the same sense that a mathematical proof is true. The 'Theory of Everything' for the mediaeval and early modern era included categorisation into associations between, for example, metals, planets, bodily organs and herbs, among other things. Our current scientific theories also constitute such a system. The difference may lie in falsifiability, but in practical terms both perform the same function when I'm trying to decide what herbs to prescribe a patient. I could look at her sympathetic nervous system as labile and decide to dampen it down with Valeriana, or I could think about preventing keloid formation and prescribe Rosa canina, probably as an essential oil, because it is a herb of Venus.

When I use astrological associations, I am not committed to belief in astrology any more than a navigator observing the stars is committed to a geocentric cosmology, but it would not help the navigator to see the Universe as heliocentric.