Act and Potency: Notes on the Structure of Being in the Summa Theologica

Abstract

The distinction between act and potency, received by Aquinas from the Peripatetic tradition and recast in light of Esse subsistens, runs through the Summa Theologica as an architectonic principle. This essay traces the early articles of the Prima Pars to show how the actus-potentia pair orders the doctrines of creation, secondary causality, and the metaphysical composition of finite being, radically distinguishing it from Being by essence.