This paper explores the implications of Aristotle\u27s puzzling suggestions that the possibility of first philosophy somehow depends on whether part of the soul is separable from material body. My Conjecture1 is that for Aristotle the science of metaphysics depends on a special activity of nous that grasps die self-identical essences which are objects of first philosophy, as distinct from physics and mathematics. From Aristotle\u27s perspective, of course, it is the existence of such essences that makes metaphysics possible, but it is arguable that without a corresponding mode of cognition this would not be a human science. It is a moot question whether it could be a divine science either, though one can argue that for Aristotle the divine mode of cognition, involving the complete identity of knower and known, represents the ideal to which human noetic activity aspires. Thus, in my title the term \u27nous’ refers to this higher-level noetic activity, as distinct from the basic noetic activity that is Common to all kinds of thinking. My argumentative strategy will be as follows. I begin with those passages in Metaphysics VI & XI where Aristotle makes his division of the theoretical sciences into physics, mathematics, and .first philosophy with respect to their different subject-matters. Next I correlate these with psychological passages in De Anima which deal with the relation between nous and different kinds of essences. Then I draw some parallels with Aristotle\u27s arguments in Metaphysics XII for the existence of an unmoved mover whose activity is purely noetic. Here we find exemplified the perfect identity of[ nous with its object which is possible for entities that are completely independent of matter and hence are pure actualities. Finally, I return to the earlier books of the Metaphysics in order to show that for Aristotle the principles and essences involved in first philosophy are only accessible through noetic insight. In this way I want to suggest that the activity of nous is foundational for metaphysics
