This paper reconstructs the Stoic theory of deixis in order to explain the importance placed by the Stoics on demonstrative pronouns and the so-called definite propositions they compose. I argue that these propositions are privileged by the Stoics on both ontological and epistemological grounds because of the semantic properties of their subjects. They are firstly privileged on ontological grounds because their subjects, which refer by deixis alone, bear a privileged relationship to matter, the most fundamental ontological category. In addition, they require the immediate graspability of their referent. Secondly, deictic expressions are privileged on epistemological grounds because they compose the most epistemologically fundamental propositions. Not all apparently demonstrative expressions will fulfil these requirements. I therefore also consider what constitutes a deictic expression for the Stoics – arguing that anaphora, for example, does not – and exactly how deixis secures reference, suggesting that, by contrast with what has traditionally been assumed, pointing is neither necessary nor sufficient.