The 1462 debate at Pius II's court between Franciscans and Dominicans on the metaphysical status of Christ's shed blood is here explained as a battle between conflicting theories on the metaphysics of human nature first developed in the late thirteenth century. Each order's theory had since become politically instrumentalized and bound to its corporate identity. A close reading of two texts produced following the debate provokes further reflection in two directions. On the one hand, the debate illuminates the interaction between scholasticism and humanism. Dominican arguments which drew upon Aquinas's writings on the human body's dignity appealed to the Renaissance humanist Pius. On the other hand, a methodological point is raised with respect to the writing of histories of ideas, namely that it would seem, pace Quentin Skinner, that it is possible to write a history of an idea in its own right alongside and compatible with a history of the uses to which the idea is put. Aquinas's theory on the metaphysics of human nature retained a power of its own, generating a vision of the human body's dignity almost in spite of the immediate exigencies of mendicant order politics in 1462.