ST. THOMAS AQIDNAS'S THEORY OF THE ACT OF UNDERSTANDING N EO-THOMISTS HAVE generally held the interpretation that St. Thomas explained understanding as a vital act in which the intellect moved itself to know another as other. That this interpretation still holds sway is evident from Leslie Dewart's statement that: . . . for St. Thomas, for instance, cognition occurred when one being acted upon another, if the other was a knower-that is, if it had the power to take advantage of this activity upon itself to posit within itself an immanent act the formal nature of which was to render him (intentionally) one with the known, that is one with that which was originally other, to which the knower was united precisely as other.1 From Dewart's statement it is obvious that the interpretation of Aquinas's theory of understanding in terms of vital act is closely associated in the minds of those who hold it with the belief that Aquinas conceived of knowledge as the way for a knower to become another as other. However sound that belief may be, it is certainly questionable that Aquinas ever analyzed understanding as a vital act. Bernard Lonergan showed some time ago that not only did Aquinas never employ the notion of vital act to explain understanding, but he never even used the notion at all. Self-movement in the soul or in any of its potencies was a notion so alien to Aquinas's thought that he precluded it from life in general and in any of its manifestations in either God or man.2 In fact, Lonergan added, in Aquinas's 1 Leslie Dewart, The Foundations of Belief (NewYork: Herder & Herder, 1969), p. 74 (emphasis in the original). • Bernard J. F. Lonergan, Divinarum personarum conceptionem analogicam (Ad 88 THEORY OF THE ACT OF UNDERSTANDING 89 time the advocates of vital act were his adversaries, the so-called Augustinian theologians, and the leading proponent o£ the notion in the years immediately thereafter was Peter John Olivi, a bitter critic of Aquinas.3 Yet, except for the ratification of Lonergan's reinterpretation by a couple of his followers,4 there is little indication that the interpretation of Aquinas's theory of understanding in terms of vital act is any less dominant today than before Lonergan first challenged it. Therefore, I propose to show, first, how necessary the notion of vital act is to the Neo-Thomistic theory of understanding, but how contrary it is to St. Thomas's. Then I shall indicate how Bernard Lonergan's reinterpretation of St. Thomas's theory of understanding led him to deny that Aquinas had ever employed the notion of vital act in it. Finally, I shall present an interpretation of how St. Thomas actually arrived at the notion of act that he used to explain understanding. The cumulative effect of this argument will be to show, I believe, that Aquinas based his theory of understanding upon his own reflections and not upon the postulate of a vital act in the intellect.5 THE NEo-THOMISTIC INTERPRETATION OF ST. THoMAs's THEORY OF UNDERSTANDING IN TERMs oF VITAL AcT In Neo-Thomism the interpretation of St. Thomas's theory of understanding has been virtually indistinguishable from an analysis of understanding itself. Partly this has been because Neo-Thomism originated as a movement from Leo XIII's manusum auditorum. Rome: Pontifical Gregorian University, 1957), pp. 248-52; De Deo Trino. 1: Pars systematica (third revised edition of Divinamm personarU'rn ... Rome: Pontifical Gregorian University, 1964), pp. 268-72. 3 Divinamm personarum, pp. 247-48; De Deo Trino, p. 267. • Frederick Crowe, " Complacency and Concern in the Thought of St. Thomas," Theological Studies, 20 (1959), 14-16; cf. footnote 33; William Stewart, "Abstraction : Conscious or Unconscious? The Ve1·bum Articles," Continuum, 2 (1964), 411. 5 This article is a reworking of part of a dissertation entitled The Meaning of Act in Understanding: A Study of the Thomistic Notion of Vital Act and Thomas Aquinas's Original Teaching, which I defended at the Gregorian University in 1969; an excerpt has been published by the Officium Libri Catholici, Rome. 90 WILLIAM E. MURNION date that Catholic philosophers and...