This paper argues, against A. N. Williams, that Aquinas accepted a doctrine of created grace, in addition to uncreated grace, throughout his career, including in the Summa theologiae. After offering analyses of Aquinas's treatment of created and uncreated grace, it further argues, against Luke Davis Townsend, that according to Aquinas created grace is the formal cause not only of a person's being justified but also of a person's participating in God and being deified. To this extent, these latter are mediated: created grace is what explains someone's participating in God and being deified: 'explains' in the sense of an Aristotelian formal cause, much as (to use one of Aquinas's examples) something's whiteness explains that thing's being white. [ABSTRACT FROM AUTHOR]