'Magic coins' and 'magic squares': the discovery of astrological sigils in the Oldenburg Letters

Enclosed in a 1673 letter to Henry Oldenburg were two drawings of a series of astrological sigils, coins and amulets from the collection of Strasbourg mathematician Julius Reichelt (1637-1719). As portrayals of particular medieval and early modern sigils are relatively rare, this paper will analyse the role of these medals in medieval and early modern medicine, the logic behind their perceived efficacy, and their significance in early modern astrological and cabalistic practice. I shall also demonstrate their change in status in the late seventeenth century from potent magical healing amulets tied to the mysteries of the heavens to objects kept in a cabinet for curiosos. The evolving perception of the purpose of sigils mirrored changing early modem beliefs in the occult influences of the heavens upon the body and the natural world, as well as the growing interests among virtuosi in collecting, numismatics and antiquities.