Reid on Leibniz's monad and the conceptual priority of the whole

In his Essays on the Intellectual Powers of Man Thomas Reid draws an analogy between his notion of the self and Leibniz's notion of a monad. Reid formulates this analogy in order to highlight what he considers to be the essential feature of the self: its unified and indivisible structure. This paper considers Reid's analogy in the specific context of the diachronic aspect of substantial unity. Its focus is specifically on the role that the idea of continuity plays in establishing the unity and indivisibility of the entities in question (viz., the self and the monad). As part of the ongoing debate over Leibniz's mature metaphysics of substance, this paper highlights the positive implication of Reid's analysis of the self (usually viewed as a critical reaction to Locke and Hume) and its place within the early modern debate over the nature of substantial unity.