As used in theology indicates the universal principle of all actuality, namely, God. Whatever is finite actuality is so because it participates in the infinite actuality of the first act (St. Thomas, Summa theologiae 1a, 75.5 ad 1). Creatures can no more act without a positive divine influence than they can begin or continue in existence independently of it. God as the first act is the cause of created action, not only by giving the created agent its form, which is the principle of action, but by conserving that form and its powers, and by concurring in the operations that flow from those powers. Since every reduction of power to operation, whether in the material or spiritual order, is a transition from potency to act, effected by something in act, God must be the first act (ST 1a, 2.3).
While God is first act, the acts of creatures as secondary agents, nevertheless, are real, efficacious, and according to their proper forms and powers (ST 1a, 105.5). Since the cause of an action, however, is more the one whose power effects it than the one who acts, God as first act is more the cause of created action than its secondary agents. How God moves the created free will freely, yet efficaciously, so that it acts freely under divine influence, is a problem about which theologians have speculated through the centuries.
See Also: causality; cause, first; free will and grace; pure act
Bibliography: a. gardeil, Dictionnaire de théologie catholique, ed. a. vacant et al., 15 v. (Paris 1903–50; Tables générales 1951–) 1.1:337–339, Tables générales 1:557–560. j. mÖller, Lexikon für Theologie und Kirche, ed. j. hofer and k. rahner, 10 v. (2d, new ed. Freiburg 1957–65). t. t. paine, h. f. davis et al., A Catholic Dictionary of Theology (London 1962–) 1:23–25.
[m. r. e. masterman]