For Böhme, creation is not mute. God did not create a world of brute, meaningless matter; he inscribed his nature in every creature so that the outer form genuinely reveals the inner spirit. The walnut's resemblance to a brain signals its properties for the head; yellow plants address the liver and bile; thorny plants carry something of the sharp, contractile first principle. This is not symbolism or poetic fancy but, for Böhme, metaphysical fact: the sign is caused by the signified.
To read the signatures of things is not merely an intellectual exercise but a contemplative one. Böhme inherits from Paracelsus the practical side of signature theory — herbalism and natural medicine depend on it — but he goes further: the ability to read the world as a divine text requires a particular kind of inner preparation. Only one whose inner ground has been at least partially restored can see through the outer husk to the spiritual seed within.
The doctrine of signatures stands in implicit opposition to the emerging mechanical philosophy of the seventeenth century, which treated nature as a machine governed by quantity and extension alone, devoid of inherent meaning or quality. For Böhme, quantity and extension are the outer shell; quality and meaning penetrate all the way through. Every creature is both mechanically describable and spiritually legible, and to understand it fully requires both modes of reading.
Böhme's signature theory influenced later Romantic Naturphilosophie — Schelling, Oken, and Baader all drew on it — and the symbolist tradition in literature. It was also absorbed into homeopathic and anthroposophical medicine, which retain the idea that therapeutic properties are expressed in a plant's outer morphology.
