The Science of Magnetism Before Gilbert Leonardo Garzoni's Treatise on the Loadstone

This paper presents the main features of the treatise on magnetism written by the Jesuit Leonardo Garzoni (1543–92). The treatise was believed to be lost, but a copy of it has been recently recovered. The treatise is briefly described and analysed. The results of a comparison between Garzoni's treatise, Della Porta's Magia Naturalis (1589), and Gilbert's De Magnete (1600) are also summarized. As claimed in the seventeenth century by Niccolò Cabeo and Niccolò Zucchi, the treatise contains quite a lot of the material to be found subsequently in the Magia Naturalis and in the De Magnete. Most importantly, the treatise presents so many interesting features, well before Gilbert's work, which make it the first example of a modern treatment of magnetic phenomena.