The Doctrine of Signatures, encoded by 16th century physician Paracelsus, is simply defined as the art of knowing the medicinal properties of plants from their outer appearance or environment. In other words… “Signatures” are signs from the plants that indicate their therapeutic attributes. Pure and simple.

This model is based on an expansive view of the universe – a “sympathetic magic” – if you will, that has been intuited by folk healers for as long as plants have been harvested and ingested for healing purposes. Although it may seem far-fetched, it is actually a logical principle that implies that two different objects or life forms resonate with each other if they share the same intrinsic character, essence, or outer aesthetic.

The ancient Chinese sages, Ayurvedic vaidyas, Native American healers, African shamans and indigenous plant doctors worldwide tapped into the Doctrine of Signatures intuiting that the key to reading a plant’s essential way of being was through observing it in its natural habitat and examining its appearance (shape, color), environmental niche, taste and smell. Through this intuitive perception, these wisdom carriers could predict which organs could be affected by a certain plant; the effect of the action itself; even the plant’s active ingredients. Simply by being with the plant in its pure form!

For example: walnuts look like human brains. Not surprisingly, they are the best nut for brain health as their significantly high concentration of DHA, a type of Omega-3 fatty acid, protects the brains of infants, improves cognitive performance in adults, and prevents or ameliorates age-related cognitive decline.

Have you ever cut a carrot and looked at the slice closely? It looks like the pupil of an eye (only its orange, not blue, black, brown or hazel, etc.) Carrots are actually excellent for our vision. Their abundance of pro-vitamin A carotenoids help protect the surface of the eye (the cornea), and have been proven essential for optimal eye health.

Ever slice a beet? Notice the color of its juice? Yup – beets are great for the blood. Beetroot juice is one of the richest dietary sources of antioxidants and naturally occurring nitrates, which improve blood flow throughout the body – including the brain, heart, and muscles. These natural nitrates increase a molecule in the blood vessels called nitric oxide, which helps open up the vessels allowing more oxygen flow, thus lowering blood pressure. 

As I’ve explored numerous examples and delved deeper into this model of watching the signs of nature, I have been stricken by an exciting similarity between the Doctrine of Signatures and Ayurveda. Both of these leave room for the mystery, the unexplainable. In Ayurveda this is expressed through prabhav - the higher influence, mysterious or hidden action of a particular substance (food, herb, etc.) One can logically conclude the taste (rasa), thermal effect (virya) and post-digestive effect (vipak) of a substance, but there may also be an action that defies explanation. In the same vein, the Doctrine of Signatures refers to arcana - the great secret of nature that the alchemists sought to discover. Both of these systems rely on the act of faith in nature and her healing alchemy, whether therapeutic agents can be perceived, or exist beyond our five senses.


Alana Greenberg