  Regius acknowledged objections, as early as 1641, to scholastic descriptions of human nature, according to which the human mind or soul was the substantial form of the body that was capable, after death, of existing on its own. As indicated above, he accepted Descartes’ general objections to the intelligibility and explanatory usefulness of substantial forms. It was unclear to him, therefore, how such forms could be used to describe or explain human nature. His reservations about substantial forms were articulated in the draft copy of Fundamenta physices, which he had sent to Descartes prior to publication. The latter’s objections caused Regius to delete three of the more controversial claims about God and the soul from the published text. However, they re-appeared in the Corollaries of Regius 1647b, and in the second edition of the text, Philosophia naturalis (1654).