Book excerpt: St. Thomas Aquinas' theology of Christ's human passions comes at the height of a medieval debate centering on the reality and extent of Christ's experience of affective suffering. Weighing in on the debate, Aquinas forges a defense of Christ's full humanity that stretches far beyond the inquiry into Christ's passions and seeks to uphold the realism of the dogma of the Incarnation. St. Thomas' doctrine of Christ's human affectivity owes much to patristic and medieval thought. Yet no less does it charter a course in Christology that stands out for its originality and depth of analysis.