Reading Aquinas’s Commentary on the Metaphysics of Aristotle. Introduction

One of the greatest works in the history of metaphysics is the Commentary on the Metaphysics of Aristotle of Thomas Aquinas. It is a work that I have longed for decades to read in the sustained and systematic way that a reading appropriate to such a work requires. Though, however, I have had a few false starts, I have never, for reasons compelling and others not so compelling, definitively set aside the time needed for that kind of reading. But I am now determined to set aside that time and undertake that reading. Not alone, however. I am establishing as one of the core threads of After Aristotle a series of posts setting forth some of the reflections that my readings of Aquinas’s commentary give rise to.

I say “my readings, in the plural,” of the commentary for two reasons. The first is that I of all people should understand that no one reading of a major work in philosophy, and perhaps more so this one than others, is enough for its full understanding. So the reading plan I have in mind includes, first, an initial reading and then one or more rereadings that will follow. Whatever will be the nature of any end result of any subsequent rereadings, the first reading will not be one in which I read and comment upon the text of Thomas in the way he does upon that of Aristotle, beginning at the beginning and proceeding line by line, passage by passage, and argument by argument, through the work until its end.

Rather, I foresee myself often understanding a line, a passage, or an argument but partially, if at all, and having to return to it later on. Thus, for example, the very first paragraph of Thomas’s “Prologue” contains several arguments; I count five. As of this writing, I on the one hand can understand and spell out and assess one of them quite to my satisfaction; this will serve as the focus of the next post. One of them, on the other hand, leaves me fairly baffled and incapable of any fully intelligible commentary on it; I think, and you might well say, “Of course you do,” that the problem lies in the argument and not in my understanding, but I do not claim to know that. And then there are the others, between the two hands. It is my hope that by the time I complete the first reading of Aquinas’s commentary, assuming that such a time ever arrives, I will be able to return to that first paragraph and offer something of a full commentary upon it. Before then, however, in this first reading, there will be much that I will have to pass over.

The second reason I spoke above of “my readings,” in the plural, of the commentary is that, even in, or especially in, my first reading, I will be reading and rereading the text and going back and forth between earlier passages, already subjected to one or more readings, and later passages that may shed light on them. I may well have to modify, add to, or delete from what I may have said in an earlier post.

One more note should be enough at this point. It is that I will also be reading and rereading the commentary in conjunction with other works, works by Aristotle, Aquinas and others, even others whose thinking is widely at variance with the Aristotelianisms of Aristotle and Aquinas; Ockham, Frege, Russell, and Quine come readily to mind. I will feel free to engage in occasional forays departing from immediate contact with the texts of Aristotle or Aquinas.

This is a project which will, should fortune smile upon me, keep me happily engaged for some years, certainly more years than it took Aquinas to write his original. It is my deepest hope that others will accept the invitation I hereby extend to enjoy it with me and to offer to me any comments, questions, suggestions, or critiques that they think what I have said might call for.

I will be using as my text St. Thomas Aquinas, Commentary on the Metaphysics of Aristotle, translated and introduced by John P. Rowan and with a preface by Ralph McInerny (Notre Dame, Indiana: Dumb Ox Books, 1995). It includes a translation of the version (or versions) of Aristotle’s text that Thomas commented upon, differing here and there and in varying degrees from the Metaphysics we know today.

The same Rowan translation of Thomas’s commentary is available online, along with and facing the original Latin, at:

If you prefer to do your reading in hard copy, you may easily purchase a copy of the work through, by simply clicking on the following:

Until next time.


About Rchard E. Hennessey

See above, "About the Author/Editor."
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6 Responses to Reading Aquinas’s Commentary on the Metaphysics of Aristotle. Introduction

  1. David Murphy says:

    Dear Prof. Hennessey, I’m excited to read about this endeavor. I can’t undertake the same journey through Aquinas’ Commentary right now, but I have consulted parts of it as well as of his commentary on the Physics. But my daily reading project is along similar lines: right now, an hour of the Metaphysics in Greek, an hour of the Summa Contra Gentiles in Latin, and then a half hour or more, depending on what it takes, to type my notes. It’s been gratifying to chug along with this regimen, which has in the last eight months on the Greek side taken my through Alexander’s De Fato as well as Ari’s Categories, AnPo and Topics.

    As a classicist, I envy your background in metaphysics and modern logic.

    I’ve been wrestling with what I (think I?) see as some discontinuities between Aquinas’ system and the Aristotelian framework in which he tries to flesh it out. It would be great if we were able to exchange some thoughts as we go along – and even if I can shoot you a question or two.

    Looking forward to further installments,

    • I am very impressed by your reading regime, both in the disciple it illustrates and the required knowledge, especially of Aristotle’s Greek. You are just the reader I hope to engage with.

      • That should have been “discipline.” I should add that I too am very much interested in the “discontinuities” that (may) exist between the metaphysics of Aristotle and that of Aquinas. I take it that Aquinas has advanced the Aristotelian philosophical perspective beyond the state in which Aristotle left it, in at least some respects. But I wonder what Aristotle would have made of the at least purportedly revelation-based theology which Aquinas and untold numbers of Jewish, Christian, and Muslim thinkers set in place above metaphysics.

  2. David Murphy says:

    Off the top of my head, I think Aristotle would totally oppose the Incarnation, as the neo-Platonists did. I think he’d oppose the doctrine of creation ex nihilo, at which we get time, since Ari’s whole discussion of motion caused by an unmoved mover that is pure act seems to demand that the motion, at least of the highest spheres, be eternal. I think he’d reject the marriage of “free will” and pure actuality in God. And I think he’d deny that Aquinas’ proofs count as demonstrations, even merely as demonstration “quia”, since Aquinas has to rely on what for Ari is “pros hen” predication — a kind of equivocation. For starters. But I am used to reading authors who say that those who disagree with Aquinas merely fail to understand Aquinas, so …

    On to your #2.

    If you have detected discontinuities betw Ari and Aq, I’d like to hear your take on them.

    • Might you have some thoughts on how Aristotle would have responded to Aquinas’s doctrine of the Trinity?

      • David Murphy says:

        I haven’t gotten that far in Aquinas yet!

        Another point on which Ari might differ is the location of the “arche” of an action. He tends to say that beings with soul are the starting points of their motions, although of course ensouled beings depend on other things for life, e.g. the sun. But to give an action of why the man went outside, it’s sufficient to say he went to the fountain to get a drink of water. Aristotle will demarcate the action of going to get the drink so that the man’s decision is the starting point, and we don’t have to trace a causal chain all the way back to the Unmoved Mover in order to give a full account of THAT action. So he resists the idea of fate. I mentioned Alexander’s De Fato. This is a big deal in there, against the Stoics.

        Aquinas on the other hand wants every event to be caused by God in a chain of causes ordered per se, no matter how many intermediate causes there are. So I think that’s another difference: no fate vs predetermination.

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