The doctrine of signatures is the age-old belief that plants resemble the very body parts they are intended to treat. The concept is perhaps as old as the history of mankind, but is believed to have taken its name from the book “The Signature of All Things” (1621) by German philosopher, mystic, and theologian Jakob Boehme.
Today we have effective modern tools to evaluate the efficacy and healing properties of plants, animals, minerals, and synthetic substances, but how did people in earlier times evaluate the natural resources available to treat their illnesses?
Well, for hundreds of years healers and medical practitioners relied on the doctrine of signatures to signal the potential healing effects of plants. In the 1st Century AD, the Greek physician and author of Materia Medica, Pedanius Dioscorides, described medicinal plants according to a divine intention. His belief was that God marked objects with signs, or “signatures”, of their purpose. This notion of divine design persisted as a central aspect of medical doctrine throughout the middle ages.
The Swiss physician Paracelsus (1493-1541) was a notable advocate of the doctrine of signatures who wrote, “Nature marks each growth…according to its curative benefit.” According to the doctrine of signatures, signals such as shape, color, and texture serve as hints to which organ a plant treats. This observable framework was both practical and spiritual, in that it afforded a means to name and categorize the natural world while adhering to the mystical and theological beliefs of the period.
While the doctrine of signatures has no bearing in modern science and medicine, its roots are illustrative of the interconnected roles of theology, cosmology, and natural science. Jakob Boehme, much like Hildegard of Bingen, was inspired by powerful visions, which guided him into a perspective of divine unity between man and nature that would underscore much of his work. This notion of interconnectedness was central to Hildegard medicine as well.
Even though the physical attributes of botanicals are unrelated to their medicinal applications, the mnemonic (memory device) of the doctrine of signatures carries on in the nomenclature of plants. Many plants were named based on their purported “signatures”. This associative naming was an effective tool for the retention and recall of the plants’ medicinal properties and uses within the human body in a time when very little was written down.
Some plants were also likely named after-the-fact, acquiring names based on their corresponding effects in the body. In either case, we’ve collected a few examples that illustrate how the naming and “signatures” according to folk medicine just happen to be relevant.
Walnuts resemble the human brain. Traditionally walnuts were considered medicinal treatment for head-related ailments. Today, we know the fatty acids contained in walnuts actually improve concentration and memory.
Naked Ladies (colchicum autumnale)
Commonly known as autumn crocus, meadow saffron, or naked ladies, the roots of this plant resemble the form of a gout-ridden toe. In fact, the bitter flavors and active ingredients (alkaloids, colchicine, and flavonoids) actually do provide effective treatment for gout.
The hairs found on the stinging nettle resemble fine needles. This appearance has drawn the plant closer to stinging-related conditions, such as insect bites, allergies, and rheumatism. The appearance of hairs all over the plant also resembles the hair on our heads. And, in fact, stinging nettle is used in traditional German medicine topically as lotions, creams, and tinctures for improving blood circulation and stemming hair loss.
St. John’s Wort
With its golden yellow blossoms, we associate the appearance of St. John’s Wort with the sun. It’s no surprise that this herb has been used for centuries to bring light into the soul, to improve moods and disposition.
The Pansy or Viola
The Latin “Viola” means “the injured” in German. The pansy or viola applies healing to psychological injuries, particularly those that manifest on the skin, the reflection of our soul. Certain skin conditions such as eczema, milk scab (in babies), or psoriasis may be associated with anxiety. The topical use of the pansy blossom may also improve rashes and acne.
Lungwort (pulmonaria officinalis)
Lungwort derives from the borage or forget-me-not family, including a variety of shrubs, trees, and herbs. The plant’s signature appearance of white spots corresponds with the spots one might find on a sick lung. In the ancient past, the popular reference for lungwort was tuberculosis (or, consumption), because of its widespread reach. Since Hildegard of Bingen’s time, the lungwort remedy was more commonly used to help in treating less dire lung conditions, such as pulmonary emphysema, bronchial coughs, and asthma.
Another bronchial plant that follows the Signature Doctrine is cowslip primrose (Primula veris), a Hildegard favorite. Much like the leaves of the lungwort, those of the cowslip have a fuzzy, lung-like appearance. Young leaves of the plant are suitable for salads or cooked like spinach. Primrose adds a light, pleasant flavor when mixed with other vegetables.
Most practical medicinal benefits are found in the root of the cowslip primrose. The flowers, though beneficial, have a slightly milder effect. The main active components of cowslip primrose are the plant flavonoids, essential oils, tannins and silica. The saponins can irritate the gastric mucosa, which stimulates the nervous system. The result is an increase in bronchial secretion, which helps to relieve some symptoms of the common cold.