To Digby's contemporaries, he is a corpusculairan philosopher committed to mechanical explanations. Typically, both corpuscularianism and mechanism are taken to entail a commitment to actual parts. However, Digby rejects actualism about parts, and endorses strong potentialism. The result puzzled his contemporaries. This chapter investigates how some of his readers responded to him on this point, with the purpose of clarifying how his corpuscularianism and mechanism play out in the context of his potentialism. I argue that, rather than the impediment to corpuscularianism and mechanism that it might seem, Digby's potentialism allows him to circumvent various problems that arise in other models.