This article explores why Herbert of Bosham (d. ca. 1194) claimed that writing history and expressing emotion were inherently incompatible activities. Focusing on the Historia that Bosham wrote (ca. 1184-ca. 1189) about the life and death of his close friend, Thomas Becket, I begin by situating Bosham's claim within the wider framework of history-writing's disavowal of the emotions. I then go on to unpack Bosham's definition of historia as a literary genre and to explain his understanding of emotional expression, using the frameworks of medieval grammar, rhetoric, and biblical exegesis to do so. While Bosham understood history-writing as a genre policed by strict "laws," I argue, he understood the emotions as inherently lawless-and thus unable to be contained by the normal rules of discourse. This means that when Bosham periodically abandoned the chronological progression that normative historical writing demanded, he was not just being the poor historian that modern scholarship has often made him out to be. Rather, he was being daringly experimental, quite deliberately using rhetoric's most emotional techniques (especially amplificatio, apostrophe, and enargaeia) in order to give his Historia a lyrical complexion. I argue here that the Historia's alternation between lyrical stasis and historiographical progression was both personal and political. On the one hand, it mirrored Bosham's own alternation between mourning and consolation. On the other, by refusing the demands of narrative progress, the Historia refuses to close the Becket conflict down and to bring it safely to a conclusion.