The distinction between the mental operations of abstraction and exclusion is recognized as playing an important role in many of Descartes’ metaphysical arguments, at least after 1640. In this paper I first show that Descartes describes the distinction between abstraction and exclusion in the early Rules for the Direction of the Mind, in substantially the same way he does in the 1640s. Second, I show that Descartes makes the test for exclusion a major component of the method proposed in the (...) Rules. Third, I argue that in Rule 14 the exclusion-abstraction distinction is connected to a theory of distinctions, which includes a notion of real distinction as essentially tied to the imagination. This sheds light on Descartes’ development in and after the Rules. (shrink)