We focus on the question of how expertise as conceived by the Stoics interacts with the content of impressions. In Section 1, we situate the evidence concerning expert perception within the Stoic account of cognitive development. In Section 2, we argue that the content of rational impressions, and notably of expert impressions, is not exhausted by the relevant propositions. In Section 3, we argue that expert impressions are a subtype of kataleptic impressions which achieve their level of clarity and distinctness (...) due to the contribution of expertise. In Section 4, we argue that the expertise in living well not only allows the wise person to assent correctly but also affects the content of her impressions. We suggest that these two models – one’s attitude toward an impression being informed by expertise, and one’s impressions being affected by expertise – might characterize distinct stages of cognitive development. Stoic wisdom is not only a matter of the way one assents to one’s impressions but also a matter of the condition of one’s soul and, consequently, of the kinds of impressions one even entertains. Expertise offers a model of how cognitive and discriminatory improvement through practice and effort can transform the non-wise into the wise. A reading on which the content of impressions is not exclusively propositional illuminates a further aspect of this transformation. If the same propositions are accessible through impressions with different non-propositional content, we can account for cases in which the novice and the expert entertain the same proposition. (shrink)