Dr Bach described himself as a herbalist and he had a knowledge of plants and medicine gained from talking to folk healers as well as from personal study. What, then, was the influence of ideas central to herbal medicine in his discovery of the 38 flower remedies? We can speculate (in the absence of any definitive knowledge!) and in this blog I’d like to consider the possible influence of one idea known as the Doctrine of Signatures.
Today this is much mocked by sceptics, but it undeniably contributed to the shaping of herbal medicine as we know it now, as well as to the discovery of some drugs used in conventional medicine. The Doctrine stated that God had marked some plants to tell us how they could be used – the leaves of lungwort (Pulmonaria officinalis) look like diseased lungs and so were used to treat lung diseases; the structure of the eyebright (Euphrasia officinalis) flower resembles an eye so the plant was used to treat eye conditions, etc. 
It was popularised by the Swiss physician Paracelsus (1493–1541) but there is evidence of its importance throughout the history of medicine. Henbane (Hyoscyamus spp.) was smoked by the Ancient Egyptians to treat toothache – perhaps as a result of the seed heads looking like a row of teeth. In fact, henbane contains hallucinogenic compounds including scopolamine which would cause users to forget their toothache for a while, even if it didn’t cure the pain permanently! 
The Doctrine was key to the writings of William Coles, a contemporary of Nicholas Culpeper but, in contrast, Culpeper believed in the astrological properties of plants. However, even Culpeper succumbed to the idea that every plant had a purpose – writing on honeysuckle that chewing it did not help a sore mouth he said, “If it is not good for this, what is it good for? It is good for something, for God and Nature made nothing in vain.”
Other aspects of the Doctrine were the idea that plants grew where they were needed and that their behaviour could also guide us to their medicinal effects. The former was important in the decision of Rev. Edward Stone to try taking willow bark to treat his agues (willow is abundant in damp conditions where agues (with malaria-like symptoms) were common). Initially, the effect of Stone’s allusion to the Doctrine was to make physicians sceptical of his report of the bark’s effects, but his work led eventually to the discovery of the drug aspirin.
But do the sceptics have a point? It’s easy to select examples either to support or dismiss the Doctrine. However, faced with finding a plant to treat a specific condition from the thousands available, where would you begin? At least the Doctrine provided an arguably logical starting point. And if healers tried a plant and it didn’t work they would move onto something else (a bit like pharmaceutical companies do today with potential drugs). In some ways this mirrors Dr Bach’s discoveries – he carefully observed the nature of plants (shown in part by their behaviour?) but also tried many plants and discarded those which did not show the desired effects.
I’ve had a think about the Flower Remedies to see if there are any whose indications might have been suggested using the Doctrine. Some are obvious… aspen with its quaking leaves suggesting anxiety; chestnut bud’s sticky coating suggesting mistakes that are difficult to throw off; walnut’s hard shell giving protection; water violet standing proud and alone in ponds and impatiens, impatiently firing off its seeds explosively.
What do you think? Any more examples? Post them on facebook here
 Science Museum; http://www.sciencemuseum.org.uk/broughttolife/techniques/doctrine
 G.Kyd, M. Sibbons, (2013); Molecules Medicines and Mischief: A Year on the Chemical Trail around Cambridge University Botanic Garden; link to book info.
 T. Breverton, (2011); Breverton’s Complete Herbal; Quercus Publishing Plc, ISBN: 978-0-85738-336-5, p176