of Aquinas is the philosophy of the , "whose transcendental value paves the most direct way to rise to the knowledge of subsisting Being and pure Act, namely to God." Aquinas defined God as the "", the subsisting act of being. See also Actus purus References Sources Cornelio Fabro, "Participation", New Catholic Encyclopedia, 2nd ed. (Detroit: Gale, 2003) 10:905–910. Pope John Paul II, Encyclical Letter "Fides et ratio", 14 September 1998, Acta Apostolicae Sedis 91 (1999): 5–88. Natale Colafati, L'actus essendi in San Tommaso D'Aquino (Messina, Italy: Rubbettino Editore, 1992). Pope John Paul II, Apostolic Letter "Inter munera Academiarum", 28 January 1999. Pier P. Ruffinengo, "L' non e ancora l' di San Tommaso", Aquinas: Rivista internazionale di filosofia 38 (1995): 631–635. Further reading Actus essendi and the Habit of the First Principle in Thomas Aquinas (New York: Einsiedler Press, 2019). Thomism Concepts in metaphysics