In his Letters to Lucilius, Seneca frequently discusses moral sententiae and their ability to elicit strong reactions of agreement and inspiration in readers or listeners. Commentators often gloss Seneca’s comments on the effect of sententiae by suggesting that he uses both rational and emotional means of persuasion, without addressing the problematic implications of this strategy. In this paper, I argue, building on Margaret Graver’s recent work, that the affective responses to moral sententiae that Seneca discusses are not ordinary, irrational emotions but stem from people’s inborn attraction toward the moral good.