The main characteristic of alchemy (also in the Latin-Christian context) is its being a structured scientifi c and operative knowledge, with however conspicuous religious and hermetic traits. The present essay examines texts (from the twelfth to the fi fteenth century) of Latin alchemy in which this double nature is particularly clear. These texts emphasize that the alchemical operative program is linked to internal betterment, prophecy, divine enlightenment, and the Scriptures. The alchemist is represented as God's elect and collaborator in "taking care" of and perfecting nature.