Doctrine of signatures

For instance, birthwort (so-called because of its resemblance to the uterus) was once used widely for pregnancies, but is carcinogenic and very damaging to the kidneys, owing to its aristolochic acid content.

[citation needed] Paracelsus (1493–1541) developed the concept, writing that "Nature marks each growth ... according to its curative benefit",[3] and it was followed by Giambattista della Porta in his Phytognomonica (1588).

Regarding Hypericum, he wrote, "The little holes whereof the leaves of Saint Johns wort are full, doe resemble all the pores of the skin and therefore it is profitable for all hurts and wounds that can happen thereunto.

Michel Foucault expressed the wider usage of the doctrine of signatures, which rendered allegory more real and more cogent than it appears to a modern eye: Up to the end of the sixteenth century, resemblance played a constructive role in the knowledge of Western culture.

The character Stephen Dedalus walking along the beach, thinking to himself "Signatures of all things I am here to read, seaspawn and seawrack, the nearing tide, that rusty boot".