Home » [Fall 2022] Metaphysics: The Depths of Act & Potency

“In long Indian file, as when herons take wing, the white birds were now all flying towards Ahab’s boat; and when within a few yards began fluttering over the water there, wheeling round and round, with joyous, expectant cries.  Their vision was keener than man’s; Ahab could perceive no sign in the sea.  But suddenly as he peered down and down into the depths, he profoundly saw a white living spot no bigger than a white weasel, with wonderful celerity uprising, and magnifying as it rose, till it turned, and then there were plainly revealed two long crooked rows of white, glistening teeth, floating up from the undiscoverable bottom.”

-Melville, Moby Dick
Chapter 133: The Chase—First Day.
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While preparing a lecture on the contribution made by Thomas Aquinas to the historical development of semiotics—particularly as it helped move understanding past the initial contributions to a Latin theory of signs constituted by Augustine of Hippo—I found that nothing was more central to the advance of this narrative than the Aristotelian doctrine of act and potency.  To understand the efficacy of a sign, that is, we need to understand relations, and to understand relations, we need to understand act and potency.

As I took one brief dive after another into the relevant texts of Aquinas—most especially his Commentary on the Metaphysics of Aristotle—I fleetingly glimpsed what seemed an endless series of wonderous observations, each more than the last deserving of a thorough investigation.  This seminar provides an opportunity for all interested to join collaboratively in making such an inquiry.

Act and potency, I must admit, have together always seemed a doctrine that—despite long familiarity with the teaching—has escaped me for its depths.  The two interrelated concepts are indefinable, but not for lack of intelligibility; indeed, they are so rich that all description leaves us infinitely short of having exhausted their meaning or their pertinence to our lives.  To think of potency is to think of what is intelligible only in the light of act, but not as itself an act; to distinguish passive and active potency is to get a foothold on the nature of change, but through something itself unchanging.  It is through the change from potency to act that we come to know what anything is; and, indeed, such a change is how knowledge itself is realized within us.

If we are to explain being—to know being—we must know and be able to explain the distinction between those elements which divide it all. We must peer beyond what eyes can see.

Ten minute lecture preview
Discussion Sessions
3:30pm ET

(World times)
Study Topics &

Week 1: Form as Cause of Being & Knowing
Lecture: Principle of Substance, End of Knowledge
» Aristotle’s Metaphysics, Book VII, c.17.
» Aquinas’ Commentary on the Metaphysics, lib.7, lec.17 (§1648–1680).
» Owens’ Doctrine of Being in the Aristotelian Metaphysics, c.12 (375-77).
Week 2: Form as Principle of Composite Being
Lecture: Intelligible Relations of Form and Matter
» Aristotle’s Metaphysics, Book VIII, c.1-2.
» Aristotle’s Physics, Book II, c.1.
» Aquinas’ Commentary, lib.8, lec.1-2 (§1681–1702).
Week 3: The One and the Many
Lecture: Infinite Material Plurality
» Aristotle’s Metaphysics, Book VIII, c.3-6.
» Aquinas’ Commentary, lib.8, lec.3-5 (§1703–1767).
» Owens’ Doctrine, c.13 (379-99).
Week 4: Definition and Distinction of Potency
Lecture: Discerning the Meaning of Potency
» Aristotle’s Metaphysics, Book IX, 1-2.
» Aquinas’ Commentary, lib.9, lec.1-2 (§1768–1794).
» Owens’ Doctrine, c.14, parts I-II (403-06).

Week 5: The Grounds of Potency
Lecture: Potency and Possibility
» Aristotle’s Metaphysics, Book IX, 3-5.
» Aquinas’ Commentary, lib.9, lec.3-4 (§1795–1822).
Week 6: Analogical Primacy of Act
Lecture: The Speaking of What Is
» Aristotle’s Metaphysics, Book IX, 6-7.
» Aquinas’ Commentary, lib.9, lec.5-6 (§1823–1843).
Week 7: Explanatory Primacy of Act
Lecture: The Existing of What Is
» Aristotle’s Metaphysics, Book IX, 8-9.
» Aquinas’ Commentary, lib.9, lec.7-10 (§1844–1894).
» Owens’ Doctrine, c.14, part III (406-409).
Week 8: The Divisions of Being
Lecture: The Governance of Truth and Falsity
» Aristotle’s Metaphysics, Book IX, 10.
» Aquinas’ Commentary, lib.9, lec.11 (§1895–1919).
» Owens’ Doctrine, c.15 (411-41).

This is an advanced seminar. View the syllabus here and learn more about Lyceum Institute seminars here. Participants should have at least basic familiarity with Aristotelian physics and Thomistic psychology before enrolling.

Lyceum Institute seminar costs are structured on a principle of financial subsidiarity. There are three payment levels, priced according to likely levels of income. If you wish to take a seminar but cannot afford the suggested rate, it is acceptable to sign up at a less-expensive level. The idea is: pay what you can. Those who can pay more, should, so that those who cannot pay as much, need not. Lyceum Institute members receive a further discount (see here for details).

One payment covers all 8 weeks.

Registration is closed.


  1. I am very interested in this topic. I will have no problem reading material, pdfs, and listening to lectures. But I have other essays I must complete this fall. My writing schedule is quite full. I am a retired professor of philosophy with strong neo-Aristotelian sympathies. I can afford to help out with my fee, but I think I should only audit. IF that is right, what do I do? (Btw, I know the work of folks like John Deely, Henry B. Veatch, and Anthony Kenny.)

    1. We would be delighted to have you audit the course, Dr. Rasmussen. If you cannot attend the discussion sessions live, they are recorded. There is no distinction in price for those who audit and for those who choose to “complete” the course (as this latter is primarily part of a budding program for enrolled Lyceum Institute members, and secondarily an additional opportunity to develop the philosophical habit for all enrolled in the seminar).

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