Instantaneous change and the physics of sanctification: "Quasi-aristotelianism" in Henry of ghent's

In Quodlibet XV q.13, Henry of Ghent considers whether the Virgin Mary was immaculately conceived. He argues that she was not, but rather possessed sin only at the first instant of her existence. Because Henry’s defense of this position involves an elaborate discussion of motion and mutation, his discussion marks an important contribution to medieval discussions of Aristotelian natural philosophy. In fact, a number of scholars have identified Henry’s discussion as the source of an unusual fourteenth-century theory of change referred to as “quasi-Aristotelianism” . My aim in the paper is two-fold: first, to show that Henry's position is not quasi-Aristotelian in the sense that scholars have supposed; second, to show that, even so, his discussion in q. 13 does involve a novel interpretation of Aristotle’s account of instantaneous change