Abstract
Inspired by Christian Platonism as developed in the late fifteenth-century Florentine milieu, the French physician Jean Fernel proposed a particular interpretation of Galen in a medico-philosophical work entitled On the Hidden Causes of Things . With this interpretation, he responded to the serious and urgent need for a reconciliation of the newly reconstituted Galen of Renaissance humanism with Christian faith. The present study examines Fernel's strategy and method in constructing this singular Galenic body of doctrine, special attention being given to the roles attributed to the Creator, the formative force, and the soul. Subsequently, an analysis of the notions of spirit and of its innate heat as indispensable instruments of Fernel's physiology will uncover the very target of his criticism of materialism