There is a popular meme going around Facebook that says that foods are good for the organs they resemble -- Walnuts are good for the brain and the prostate, Kidney Beans are good for the kidneys, etc.
It's a simplified version of an old belief: the Doctrine of Signatures, the idea that the physical form of a plant suggests something about its medicine.
The doctrine is often ridiculed by rationalists as "magical thinking." Being a witch, I personally find some magical thinking quite useful. But, I insist that my own magical thinking be grounded in my experience of the world, and I attempt to bring the same precision and care to it that any other art or science would demand. Sloppy thinking is sloppy thinking, be it magical or scientific.
The version of the Doctrine of Signatures most people are familiar with today comes in the form of a system of correspondences: yellow plants act on the liver, plants with big leaves act on the skin and the lungs. Such correspondences often prove true, but divorced from the gnosis from which they were initially derived, they lose some of their power to illuminate deeper and more particular truths about the plants we encounter.
The way I see it, the "signatures" of plants are products of direct observation, and as such are particular to the time and place in which they are observed, the cultural and personal framework through which the observer is interpreting the information, and the relationship between the person and the plant. Signatures not are fixed signs communicating an absolute truth about a plant, but rather representations of our own minds' interpretations of the information plants are sharing. Stephen Buhner posits that human-plant communication occurs, in part, when the brain receives information about the fluctuation of the electromagnetic field of the heart as it comes into contact with the electromagnetic field of a plant. It makes sense to me that the mind would translate some of that information in symbolic terms, giving the sense that a particular aspect of the plant's form conveys a particular meaning.
So, if signatures are particular to a time and place and set of relationships, why do different herbalists perceive similar signatures when they encounter the same plant?
Just as different people encountering the same person in different situations might describe the same personality traits, so too different people encountering the same plants in different situations will often notice similar qualities. And of course the minds of people within the same culture draw on similar symbols. Drawing on these shared symbolic languages, it is possible to describe plants in ways that evoke something of their magic and medicine, pointing others toward contact with some aspect of their being. In contrast, the Facebook meme that I mentioned above exemplifies a common misconception -- the idea that the classical Doctrine of Signatures taught that God shaped things in such a way that their form reveals their usefulness for humans. This is a gross oversimplification and misunderstanding of the writings of mystical scientists and philosophers like
Jakob Boehme and
Paracelsus whose writings defined western understandings of the doctrine in the sixteenth and seventeenth centuries. Both believed, as Matthew Wood writes, that "the whole natural world corresponds to the archetypal world, which gives it form and meaning." They saw ours as a world in which archetypes, fallen into the realm of matter, take on imperfect physical forms. They believed that human intuition could recognize the patterns in the physical world that reveal archetypal form and meaning. Rather than believing that the forms of plants reveal hidden messages from God about the plants' uses, they saw signatures as gateways to understanding and perceiving plants in their original, perfect, immaterial forms.
Embedded in modern misunderstanding of the Doctrine of Signatures is the assumption that other beings were created for the benefit of humans, a belief that is often extended into the human sphere as well -- the idea that women were created for the benefit of men, that people of colour were created for the benefit of white people. Such ideas found their most disturbing expression in the "science" of phrenology that used the size and shape of human skulls as a way of justifying eugenics and white supremacy. Nothing in the work of Paracelsus or Boehme supports these notions.
But the work of Paracelsus and Boehme is rooted in the view that our world is fallen and imperfect -- a belief I do not share.
The particles that make up my body were present at the birth of the universe. So were the particles of every Redwood and of the soil and air and water and sun that sustain us. Because of this, I believe that nothing is separate from the divine; we are all part of divinity experiencing itself in infinite variety. From this perspective, signatures can be seen as representations of how one part of the living world experiences and understands another.So I believe in holding the Doctrine of Signatures lightly -- viewing signatures as organic poetry emerging from the encounter of beings inhabiting different bodies and speaking in different ways. And like all poetry, signatures have life when they are felt viscerally, die when they are memorized and recited by rote, and mislead when they are taken too literally.
In reference to the need to raise awareness about how the viruses are transmitted or what the symptoms are, this year's theme for World Hepatitis Day is "This is hepatitis....It's closer than you think. Know it. Confront it. Get tested." 
