  Henricus Regius (in Dutch: Hendrik de Roy) may be recognised today primarily as one of Descartes’ correspondents. However, he was also the author of a textbook of natural philosophy, Fundamenta physices (1646), which offered a significant alternative to Cartesian epistemology and metaphysics. His correspondence with Descartes, and his simultaneous controversy with G.  Voetius during the 1640s, reflected Regius’ efforts to establish his intellectual independence from scholastic philosophy and Cartesian metaphysics.