Ever wonder about how we figured out that some plants can treat certain disease conditions? For example, that the foxglove contains a compound that can treat heart issues (wiki post on digoxin here). Well, Matt Simon has written a terrific piece for wired.com that explains why some of the plant medicines we use, and a lot of the plant medicines we don’t use, were first tested. It is based on using plants that resemble an organ to treat problems with that organ.

Such thinking, known as the doctrine of signatures, actually developed with remarkable frequency all around the world from culture to culture. Plants meant to heal certain organs and body parts, like the liver or the eye, must show a certain “signature” by resembling the thing they treat.

Check out Simon’s article for a fun history lesson about some early science of medicine! Turns out that the doctrine of signatures was’t such a good one.