How Did Regius Become Regius? The Early Doctrinal Evolution of a Heterodox Cartesian

This article offers an assessment of Henricus Regius's (1598-1679) pre-Cartesian sources and their role in his appropriation of Descartes's ideas, via two main questions: 1) Who was Regius, doctrinally speaking, before his exposure to Cartesianism? And 2) how did he use Descartes's theories before his quarrel with Descartes himself in the mid-1640s? These questions are addressed by means of a textual analysis that concerns his theory of matter. In this article, I will show that 1) Regius started out with a scientific program he had found in Ramism and the medical theories of Heurnius and Santorio. 2) On this basis, he developed a physiology encompassing Descartes's theory of blood circulation and sensory perception. 3) Regius completed the resulting physiology with a theory of matter more developed than Descartes's, and which he appropriated from Santorio, Basson, and Gorlaeus.