The doctrine of signatures is an ancient way of divining the medicinal qualities of an herb through observation of its physical appearance, underpinned by the belief that “like treats like.” This concept has been foundational to the relationships forged between humans and plants, as we have made determinations about the ability of substances to treat that which they resemble. Although called the doctrine of signatures in the West, this method can be traced to cultures around the world, and its mirror in Eastern tradition is “like treats like.”
“Like treats like” might seem straightforward, and it can be, as physical appearance often offers clear clues about the medicinal properties or organ affinities of an herb. For example, Lion’s Mane resembles the brain and indeed supports cerebral and cognitive function, helps to enhance focus and memory, and aids those with neurodegeneration. It also has downward-cascading spines that resemble our nervous system, and it is a wonderful nerve tonic. Another application of this concept would be eating an animal’s organ in order to nourish that organ in one’s own body, e.g., beef kidney for Kidney health.
However, this method goes much deeper when we consider how the forces of nature influence the creation of signatures. As master herbalist Matthew Wood writes, “Every plant represents a finely honed response to environmental stress – the exact same stress that human beings must contend with in order to stay healthy. The wide array of chemical compounds in the plant, as well as its shape, color, and environmental niche all represent adaptations to stress… It is a survivor and what it can do for itself, it can convey to us as a medicine.” This connects to the concept of Di Tao in TCM, asserting the importance of habitat on the activation of an herb’s constituents, which can then manifest as observable characteristics like color, texture, scent, and growing conditions.
Of course, honoring the influence exerted by the forces of nature is foundational to Chinese Medicine, with the Five Elements framework further supporting the ability to draw profound insights from “like treats like.” This framework reveals established connections between element, color, organ system, emotion, season, and flavor to draw meaningful insights about energetic properties. For example, it can be inferred that Jujubes support the Blood due to their red color – also associated with the Heart, where Shen is stored, pointing to the emotional support they offer. Another example is the affinity of green herbs to the Liver, both of which are associated with Spring, when we are blessed with an abundance of fresh, wild herbs.
Another beautiful aspect of “like treats like” is its encouragement of a holistic perspective. In modern times, when the constituents of a plant are constantly being isolated in order to determine an effect, the doctrine of signatures reminds us to observe the whole food or herb for clues about its variety of interconnected and synergistic properties. As we engage our senses and hone our capacity to draw connections, we understand that our Qi is mirrored in nature and remember our place in the web of life.