page_title: Doctrine of signatures
hierarchical_section_title: Doctrine of signatures
caption_attribution_description: Eufrasia officinale - Località&#160;: "Giardino Botanico delle Alpi Orientali", Monte Faverghera (BL), 1500 m s.l.m.
context_page_description: The doctrine of signatures, dating from the time of Dioscorides and Galen, states that herbs resembling various parts of the body can be used by herbalists to treat ailments of those body parts. A theological justification, as stated by botanists such as William Coles, was that God would have wanted to show men what plants would be useful for.
  It is today considered to be pseudoscience, and has led to many deaths and severe illnesses. For instance birthwort, once used widely for pregnancies, is carcinogenic and very damaging to the kidneys, owing to its aristolochic acid content. As a defense against predation, many plants contain toxic chemicals the action of which is not immediately apparent, or easily tied to the plant rather than other factors.
context_section_description: The doctrine of signatures, dating from the time of Dioscorides and Galen, states that herbs resembling various parts of the body can be used by herbalists to treat ailments of those body parts. A theological justification, as stated by botanists such as William Coles, was that God would have wanted to show men what plants would be useful for.
  It is today considered to be pseudoscience, and has led to many deaths and severe illnesses. For instance birthwort, once used widely for pregnancies, is carcinogenic and very damaging to the kidneys, owing to its aristolochic acid content. As a defense against predation, many plants contain toxic chemicals the action of which is not immediately apparent, or easily tied to the plant rather than other factors.
caption: Eyebright was used for eye infections, owing to the supposed resemblance of its flower to an eye.