“Parvus error in principio magnus est in fine”: Thomas Aquinas’s Reinterpretation of the Understanding of Being and Essence as the Basis for the Discovery of the First Cause as Ipsum Esse

Keywords: being, essence, God, Ipsum Esse, proof, metaphysics


In this article, the author notes that Thomas Aquinas, in his brief work entitled De Ente et Essentia, proved that at the base of understanding the world, the human being, and God in particular, there is our understanding of being and its essence. When we make a small mistake at the beginning (parvus error in principio) in our understanding of being and its essence, it will turn to be a big one in the end (magnus in fine). And what is “at the end” of our knowledge is the discovery of the First and Ultimate Cause of all things, known as: Ipsum Esse, God, the Absolute, The Most Perfect Substance, on whom everything depends, and who depends not on anything else. These present inquiries about the proper understanding of being and its essence are aimed at formulating proof of the necessity of existence of a Being that is the First Cause, and which, existing as Ipsum Esse, is the source and reason of existence of all beings. Without these inquiries, the proof itself would be incomprehensible, and more importantly it would be a purely a priori one (i.e., ontological). Furthermore, without the existential conception of being, which Thomas first formulated, one could not discover the First Cause which, as Ipsum Esse, is the source of the existence of every being. This issue seems to have escaped the attention of the author of the book Aquinas’s Way to God. The Proof in “De Ente et Essentia.”

Author Biography

Andrzej Maryniarczyk, The John Paul II Catholic University of Lublin, Faculty of Philosophy

Prof. Andrzej Maryniarczyk, S.D.B. — Professor of Philosophy at the John Paul II Catholic University of Lublin, Head of the Department of Metaphysics


Aristotle. Categories. Translated by E. M. Edghill. Adelaide: University of Adelaide Library, 2015. Text online: https://ebooks.adelaide.edu.au/a/aristotle/categories/. Accessed August 11th, 2019.

Aristotle. Metaphysics. Translated by W.D. Ross. Adelaide: University of Adelaide Library, 2000. Text online: https://ebooks.adelaide.edu.au/a/aristotle/metaphysics/book4.html. Accessed August 11th, 2019].

Kerr, Gaven, O.P. Aquinas’s Way to God. The Proof in “De Ente et Essentia. Oxford: Oxford University Press, 2015.

Krąpiec, Mieczysław A. Metafizyka. Zarys teorii bytu [Metaphysics: An outline of the theory of being]. Lublin: TN KUL, 1978.

Maryniarczyk, Andrzej. Dlaczego stworzenie „ex nihilo” [Why Creation ex nihilo?]. Lublin: PTTA, 2018.

Seńko, Władysław. “Wstęp [Introduction].” In Thomas Aquinas. Byt i istota [Being and Essence]. Translated and commented by Władysław Seńko, 13–24. Kęty: Wydawnictwo Marek Derewiecki, 2009.

Thomas Aquinas, On Being and Essence. Translated by Armand A. Maurer. Toronto, Canada: Pontifical Institute of Mediaeval Studies, 1965. Full text online: https://dhspriory.org/thomas/DeEnte&Essentia.htm. Accessed August 11th 2019.

Thomas Aquinas. Summa Contra Gentiles. Taurini: Ex Officina Libraria Marietti, 1967.

Tomasz Sutton [Thomas of Sutton]. De esse et essentia. Translated by Piotr Kordula. Introdustion by Dawid Lipski. Warszawa: Wydawnictwo von borowiecky, 2018.

Tomasz z Akwinu, św. [Thomas Aquinas, St.]. O bycie i istocie [On being and essence]. Translated by Mieczysław A. Krąpiec. Lublin: RW KUL, 1994.