The chapter claims that in order to understand Locke’s doctrine of assent, his philosophy of mind needs to be seen in conjunction with his philosophy of language, which in turn gains from being compared with Port-Royal’s logic and grammar. It points out two conflicting facts in Locke’s account of affirmation and negation in the Essay. First, Locke entrusts affirmation and negation with the task of signifying both the assertion by which we manifest our assent to a proposition and the junction or separation of the ideas constituting the proposition. The other fact is that Locke accepts a great variety of ways of considering a proposition. This diversity of ‘postures’ is poorly expressed by the limited number of syncategorematic terms, ‘particles’. The first fact fosters a one-act view of the assent we give to propositions. The second opens the way to a multiple-act view.