An important concept in most schools of herbalism is that of the doctrine of signatures. The doctrine of signatures states that the herbs will, in some way, physically resemble their realm of therapeutic action. The resemblance may be obvious or hidden, but searching for it and seeking to understand it can help us in our quest to understand how herbs impact the human body.
In some way, the same universal forces that acted to shape the human body, disease processes that impact it, and the forces of healing that rectify imbalance are all also acting on the plants and other materials that make up the herbal materia medica. Everything is connected and exerting influence on everything else.
Basic doctrine of signature categories and some Chinese examples
The most basic level of the doctrine of signatures pertains to the color, shape/texture or habitat/behavior of the herb in question. These properties in one way or another point to its healing characteristics.
Qing Pi 青皮: Immature Bitter Orange Peel
The name of Qing Pi literally translates to blue-green peel, so this herb has a double dose of symbolic relevance! Although the dried herb doesn’t have much of a green tinge, the unripe fruit is greenish. This green color (and the “green” quality of immaturity) strongly resonates with the color of the Wood element and especially the Liver organ system. One of this herb’s primary functions is to move Liver Qi as is present in Liver Qi Depression with symptoms like chest and hypochondriac distension and pain.
Xuan Shen 玄參: Scrophularia root
This is another herb with a color in it’s name – Xuan is one word for black, but can also mean dark, mysterious or profound. Scrophularia root is dark in color and the best quality is quite black. This color resonates with the Water element, and especially the Kidney. The herb does go to the Kidney channel and though its primary function is to clear heat, it has a strong ability to tonify the Yin of the body, perhaps especially of the Kidney (using TCM terminology).
In this case, the shape of the herb relates it to the part of the body it works on. Lian Qiao looks like a chambered heart when the fruit is split in half (see picture at left). This would seem to relate it to the Heart. Indeed, this herb is in the category of herbs that clear heat – a common pathogen of the Heart organ system – and is especially good at clearing Heart/upper burner heat which might result in fever, insomnia and difficulty thinking.
Gou Teng 鉤藤: Gambir vine
You only have to look at Gou Teng once to be impressed by it. The hook shape can be thought of as useful in “hooking” something gone astray. In this particular case, the hooking is done on Liver Wind uprising, which can cause tremors and seizures. One of my favorite applications of the Doctrine of Signatures!
Habitat (plant, animal)/Behavior (animal)
One good example of a plant that exhibits healing qualities based on its habitat is Fu Ling 茯苓 : Poria
This is a kind of fungus that grows around the roots of pine trees. In that relationship, it acts as a drainer for the soil around the roots of the tree, keeping it growing strong. It does this same thing for the human body, leeching out dampness and allowing for a smooth Spleen function.
In the animal realm, we can look at Bie Jia 鱉甲 : Soft shelled turtle shell as a prime example. This animal dives into water, but perhaps more importantly, is known for burying itself in the sand. These two behaviors resonate it deeply with the Yin. One of its primary actions is to nourish the Yin. I believe it is also a snapping turtle, and this would help to explain its effect of invigorating the blood and breaking up clumps and nodules.
There are many other examples in all of these categories, of course, but these are some of my favorites. I discussed some Doctrine of Signatures information in my article on Mu Zei, shavegrass.
Are the Chinese herbal properties of flavor and nature also based on the doctrine of signatures?
On some level, the wei and qi of herbs is an aspect of the doctrine of signatures, albeit on a more subtle level. The quality of pungency, for instance is a flavor that reminds us of outward movement, agitating motion and an opening quality. Pungency of herbs does all of these things and the most pungent herbs resonate deeply with these properties. So, although not all Chinese herbs bear obvious physical manifestations as in some of the examples above, they all have properties that resonate with the impact that they have. But of course, this is to be expected.
Are we discovering or inventing?
I’ve sometimes had problems taking the doctrine of signatures seriously. One reason is it’s lack of consistency. There is a diverse range of meanings the doctrine of signatures is given – the herb can resemble (closely or simply symbolically) the part of the body effected by the disease process, it can resemble the disease itself or it can resonate with the healing process in the body impacted by the condition in question. Additionally, if some herbs work within the more obvious and explicit doctrine of signatures theory (color, shape, behavior – not Chinese properties) – why not all of them?
However, even if it is just a convenient human construction – it’s a great deal for students of herbal medicine. I remember herbs so much better with which I have established a strong mnemonic based on the doctrine of signatures! When I learn a new herb, I work hard to find a way that the doctrine of signatures fits.
I’d be very interested to hear about your understanding of the Doctrine of signatures and any fun examples you have of herbs that are easy to explain using this theory. Write to me in the comments!