  One might try assimilating this line of thought to those passages where Augustine has in mind necessary a priori truths. But it is more natural to take this in a different way, as an account of how the mind goes beyond the sensible data to a grasp of the real essences of things. Accordingly, the theory of divine illumination would be put to two very different sorts of work in the later Middle Ages: as an account of a priori knowledge, and as an account of concept formation. Each account raises its own set of issues. Taken in the first way, divine illumination has to compete against the claim that the mind is naturally capable of grasping such truth. Taken in the second way, questions immediately arise about the nature of conceptual knowledge. Do essences (or properties in general) exist in the physical world? Do they exist only in the divine mind? Do the senses play any role in the process of concept formation? Later medieval philosophers would handle these issues in interestingly different ways.