This paper will take up horror in its etymological sense as a shuddering kind of experience. I trace how this concept attaches to a particular mode of witnessing from Plato (particularly through his fifteenth-century Latin translator, Ficino, who used the word exhorreo to translate the Greek δυσχεραίνοι, often now translated as “disgust" on account of the influence of Charles Darwin’s The Expression of the Emotions in Man and Animals) to Augustine (who asked: "What sensual pleasure is to be had in viewing a mangled corpse which causes you to shudder (exhorreas)? Yet if there is one lying anywhere, people congregate in order to be afflicted and turn pale,” Conf. 10.35.55). I deploy these examples to break down the affective border between the instinctive and the performative in the act of witnessing a horrible sight.