The Doctrine of Limitation
 of Act by Potency:
Aristotelian or Neoplatonic?


Jude Chua Soo Meng
National University of Singapore


Recent developments in Thomism have highlighted the influence of Neoplatonism in what has traditionally been called the Aristotelian-Thomistic Metaphysics of St. Thomas. Some have gone to the point of suggesting that key elements in St. Thomas’ thought are untraceable to Aristotle.  Rather, they say, these have their sources in Neoplatonic writers. Of these key elements, we include the Doctrine of Limitation. Fr. Clarke SJ, for example, argued that this doctrine is not to be found in Aristotle.  Rather, it comes from an inspiration which is Neoplatonic - chiefly the Liber de Causis. In this paper we will excuse Fr. Garrigou-Lagrange OP of the charge of misinterpretation in this regard. We do this by distinguishing the Doctrine of Limitation of act by potency from its application in different orders. Our reply is that the Doctrine is truly Aristotelian, although its particular application to the metaphysical order is not.   



And so Fr. W. Norris Clarke SJ in an important article The Limitation of Act by Potency argued that Fr. Reginald Garrigou-Lagrange OP was mistaken when he claimed that the metaphysical ideas of St. Thomas were already latent in The Philosopher. The Dominican Thomist had laid down his final positions in his “Summa Thomistica”, Reality: a Synthesis of Thomistic Thought, from which Fr. Clarke SJ quotes:


“Aristotle already taught this doctrine.  In the first two books of his Physica he shows with admirable clearness of truth, at least in the sense world, of this principle.  Act, he says, is limited and multiplied by potency.  Act determines potency, actualizes potency, but is limited by that same potency…Aristotle studied this principle in the sense world.  St. Thomas extends the principle, elevates it, sees its consequences, not only in the sense world, but universally, in all orders of being, spiritual as well as corporeal, even in the infinity of God.”[1]


Upon this text Fr. Clarke comments, under a section heading “THE PROBLEM”: 


“…despite the categorical assertion of Father Garrigou-Lagrange in the above quotation, neither here nor anywhere else in his numerous writings on this doctrine does he ever quote or refer to any precise text where Aristotle himself affirms the limiting role of potency with regard to act. What is more disconcerting, a careful examination of the entire first two books of the Physics, referred to as teaching the doctrine clearly, reveals that nowhere in them does there occur any mention of the word or idea of limit in connection with potency.  Nor have I been able to find in any other Thomistic author a precise reference to any text of Aristotle which would bear out the above position.”[2]


The immediately pertinent context here is, of course, the doctrine of the limitation of existence as act by essence as potency, which the Jesuit Father wishes to trace absolutely to a Platonic heritage. He analyses the Thomistic act and potency doctrine thus, “the first is a composition of two correlative metaphysical principles called act and potency, first introduced by Aristotle to explain the process of change” - we have no argument with this - “…The second is the relating of these two principles to each other in terms of a theory of infinity and limitation, which it must be admitted by all, cannot be found explicitly in Aristotle.”[3]  This latter conjunct, we must further examine. For there is certainly the truth, as Fr. Clarke SJ would have us note, that St. Thomas was greatly influenced by certain Neoplatonic texts, chief amongst them the Liber de Causis but to rob the Philosopher of his substantive role as an efficient and particularly formal cause of St. Thomas’  doctrine of the limitation of act by potency to the point of wanting to call Thomism an “Aristotelianism specified by Neoplatonism”[4] seems excessive. We must therefore make a precise investigation to state clearly Aristotle’s direct, if not “explicit”, contribution to the thesis. For if I affirm that “1+1=2” (and further, for whatever purpose it matters not), though I do not make explicit that “{1+1}+{1+1}={2}+{2}”,  I may be also credited with the direct affirmation of the same, since to deny it would be to contradict myself, as the rule of modus tollens would have it.




Let us look at the text again. When one looks at the original quotation from Reality,  in the middle of the text which Fr. Clarke SJ picks out, Fr. Garrigou-Lagrange OP writes:


“Act determines potency, actualizes potency, but is limited by potency.  The figure of Apollo actualizes this portion of wax, but is also limited by it, enclosed in it, as content in vessel, and as such is no longer multipliable, though it can be multiplied in other portions of wax or marble.”[5]


In another pertinent text of Fr. Garrigou-Lagrange OP’s seminal work, God: His Existence and Nature, from which epilogue we read,


“When what was in potency is in act, there is still a real potency underlying the act that it receives; the wood, having already the form called statue, can lose it and  receive another.  But as long as the form called statue remain in the wood, it is received and limited by it. This same numerically one form is no longer susceptible of participation, although a form in every aspect like it can be produced in other matter of this kind.  Thus is explained the multiplication of Apollo’s form, for instance, according as it can be received and is so, in fact, in the diverse kinds of second matter: wood, earth, marble, etc., and thus it is susceptible of unlimited participation.”[6] 


Or again in Reality,


“Form, of itself unlimited, is limited by potency into which it is received.  The form then, say of Apollo, can be multiplied by being received into different parts of wood or marble…The form of Apollo, as long as it remains in this particular piece of wood, is thereby limited, individualized, and as such, irreproducible.”[7]


As the two texts of Fr. Garrigou-Lagrange OP indicate, form as act experiences a limitation when received in matter - why: because it is “susceptible of unlimited participation”, or “multipliable”, able to be in many things (or more precisely, able to be received in many second matters), but once it is in wood, for example, this cannot be the case; rather, it is “stuck” as it were, in this here-wood, i.e., limited: limited from being susceptible of  participation. Or again, “[t]he specific form of lion, a form which is indefinitely multipliable, is, by the matter in which it exists, limited to constitute this individual lion, this begotten and corruptible composite.”[8]

Now, it is obvious that limitation in this context means some form of restriction, such that that which is being limited is prevented from being unlimited.  There is no attempt at a tautology here.  The point is that when something which of its nature can do such and such but now is being prevented from doing so, it is limited from that which it could formerly do. The case in point being the form, which can be at many locations, now when in wood or wax for example, is located in the here, in this wood or wax.  Then we may further ask the question, Now that it has been limited, what is the cause of this limitation?  The answer to this question, which is matter,  will inform us of what it has been limited by, given that it has been limited.  But the thing to note is that there is nothing particularly special about this notion of limitation.  It simply means some form of restriction.  

Therefore when the Jesuit Thomist writes,


“It is quite true that he [Aristotle] does teach explicitly that forms of themselves are unique and can be multiplied only by reception in matter.  But nowhere does he say or imply that such multiplication involves a process of limitation by matter of form which by itself could be called infinite.  On the contrary, he insists against Plato that every specific form is received whole, entire, and equally in every individual of the species.


The guiding image here is clearly not that of matter or potency as a container which contracts the plenitude of form or act;  it is rather that of form as a stamp or die, fully determined in itself, which is stamped successively on various portions of an amorphous raw material as wax or clay.  Such a multiplication can appear rather as an expansion than as a limitation of the form.  The two perspective are quite different, though, as St. Thomas has shown, by no means mutually exclusive.”[9]


we may reply as follows.  Firstly, there was never the claim that form was infinite.  What is claimed, rather, is that it was capable of  multiple participation.  This is evident, because the form can be impressed into many waxes or clay or wood.  Nor have we any trouble with the fact that the stamp or die is fully determined in itself, because we never claimed that it was not.  When the form enters in composition with matter - yes, the claim is that the form is limited but not in the sense of being contracted as this only applies to essence and existence (esse) and not to form and matter.  Rather, it is now limited from its previous unlimited-ness as regards participation in second matter.  The point is some form of restricted-ness.  

          Had our position been otherwise we would have been the object of Cardinal Cajetan OP’s criticism, which says, “consider closely this position for understanding the many things said above and in order to avoid the error of those who do not understand the fundamentals of these matters.  They say that if being (esse) is therefore without qualification infinite, as we said above, because it is received in nothing, then the essence both of immaterial and of the composite substances as being wholly unreceived in anything will be infinite without qualification.  Now this is nonsense.  Consequently, it looks extremely foolish to argue to infinity for non-reception.”[10] 

On the contrary, we affirm that 


“every thing able in its own order to be received in another, and in fact not received, is infinite with the kind of infinity opposed to the finiteness which a thing contracts when received in its own order.  I said able in its own order to be received in another, because of composites and matter, which in no situation whatever can be received.  I said infinite with the kind of infinity opposed, etc. because not just anything can be received in any other whatever, but each act has its proper receiving subject, as is said in II de Anima.  Thus not just any limitation follows from any reception whatever, but a definite limitation from a definite reception. And shifting to opposites, from the lack of reception of a certain kind there follows a certain kind of opposed infinity, namely, opposed to that limitation which the thing would have contracted had it been received. Here is an example.  If whiteness, as being receivable in a subject, be given as unreceived, it will be infinite; not however with just any infinity, but with one opposed to the limitation it has in a subject.”[11]


Secondly, to say that the Aristotelian picture of multiplication of forms is an expansion rather than a limitation is simply an equivocation of words.  True enough, it is an expansion: expansion as multiplication.  But in that expansion, each form whilst formerly capable of being anywhere else, is now located in this wax or clay. It has been limited. We must keep in mind that our intention is always the form.  When we are talking about the form, in matter it is restricted whilst even being expanded. The numbers are expanding, yes; yet each form is being localized, limited.

Fr. Clarke SJ therefore confuses two issues here, which we must distinguish.  The fact that act is limited by potency is one thing, whilst the way which potency limits that act is another.  These two are by no means similar, for while the first equally applies to the order of physics and metaphysics, the second differs as to its application to both orders: in the sensible world matter limits potency by preventing it from unlimited participation, as we have seen and shall see further; in the supra-sensible world, essence restricts existence (esse) by way of contraction. Thus again the Cardinal,


“Now, in what was proposed, the being (esse) as well as the form, each according to its own order has the character (rationem) of being receivable (for neither excludes being received), but the receivers are different.  The proper receiver of being (esse) is itself a quiddity or a supposit; of form, indeed, matter.   And therefore, just as the reception of form in matter is of a kind (rationis) different from the reception of being (esse) in essence, as we said above, so the limitation of form by matter is of a kind (rationis) different from the limitation of being (esse) by essence, although they have in common that each limitation takes place in the way act is limited by potency.  Likewise there ought to be a difference in kind (rationum) between the infinity which form acquires because not received in matter, and the infinity being (esse) acquires because not received in any quiddity.  For form is closed in when received into matter below itself and loses its universality (amplitudinem), by which it is not determined to this or that particular thing.  And consequently because it is separated from matter, form is in no way infinite except that it lacks its limits, because not restricted to the capacity of some matter.  Being (esse), however, is restricted to its genus or species by being received in some quiddity.  Granted it be not received, being will be limited to no genus, and consequently, lacking the limits of any genus, will be infinite without qualification.”[12]




We defend therefrom the thesis that the maxim, that act is limited by potency, is undeniably traceable to Aristotle, although only the first of the two possible applications of the same maxim - i.e., that matter limits form in such and such a way in the sensible order - is from the Philosopher. This is clearly proven in the following.  

That according to Aristotle things are found to be in two states beyond nothingness or privation is found in the Physics (and in the Metaphysics), as Fr. Garrigou-Lagrange OP directs us[13], where Aristotle proves against Parmenides the possibility of becoming and against Heraclitus the possibility of static being. Specifically, Aristotle writes in the Physics I, VIII, 191b 20-29, referring to the application of the distinction between per se and  per accidens (elaborated earlier in 191a 33 - 191b18):


“…there can be no coming to be out of what is or of what is, except by virtue of concurrence [per accidens]… We have already said what it means to say that something comes to be out of what is not: it means out of what is not, as something which is not…That is one way of handling the matter, another is to point out that the same things may be spoken of either as possible [potency] or actual [act]. That, however, is dealt with in greater detail elsewhere.”[14]   


St. Thomas comments on this passage like this.  Referring to the approach which explains the becoming of being from both being and non-being which applies the per se and per accidens distinction, he notes, 


“This then, is one way of resolving the problem raised above.  But this approach is not sufficient.  For if being being comes to be per accidens both from being and from non-being, it is necessary to posit something from which being comes to be per se. For everything which is per accidens  is reduced to what is per se…In order to designate that from which a thing comes to be per se, he adds a second approach where he says, ‘Another consists…’ (191 b 28).  He says that the same thing can be explained in terms of potency and act, as is clearly indicated in another place, i.e., in Met aphysics, IX. Thus a thing comes to be per se from being in potency; but a thing comes to be per accidens from being in act or from non-being.”[15] 


St. Thomas then explains that it is matter, for Aristotle, which is this “being in potency” from which being comes to be per se, before he would further note how Aristotle distinguishes matter from privation:  


“[Aristotle] says this because matter, which is being in potency, is that from which a thing comes to be per se.  For matter enters into the substance of the thing which is made…Thus a statue comes to be per se from bronze.”[16]


From the texts above, it is very clear that Aristotle and St. Thomas identified the proper solution to the explanation of change or of becoming in terms of matter as potency and form as act.  That is, we must posit beings as composed of the principles of (form as) act and (matter as) potency in order to explain the phenomenon of becoming in these.    This immediately presupposes their real distinction:


“These substantial changes presuppose a pure potency, that is to say, a subject purely determinable and in no way determined.  If it were otherwise, the subject of these changes would already be a substance, and these changes would, for the same reason, be accidental and not substantial.  But this pure potency or this pure capacity for a substantial form, is neither nothingness (ex nihilo, nihil fit) nor the simple privation nor the simple privation of the form to be acquired nor something substantial that is already determined, “non est quid, nec quale, nec quantum, nec aliquid hujuhmodi: it is not a quiddity, nor a quality, nor a quantity, nor anything of this kind,” neither is it the initial realization of the form nor the imperfect act, just as the wood as determinable subject, which will become a statue, is not the statue in the imperfect state, since this begins to take shape only as the result of the sculptor’s labor; the imperfect act here is the movement, but not the real potency required for this movement.  This capacity for the substantial form is therefore a certain reality, a real potency which is not the form, but is opposed to it, as the determinable is opposed to the determining.  Moreover, this real potency can lose such substantial form and receive another: corruptio unius est generatio alterius, the corruption of one thing is the generation of another.   Thus it is evident that matter is really distinct from substantial form.”[17] 


And if matter is really distinct from substantial form, i.e., potency is really distinct from act, then matter limits the substantial form which it receives, or, potency limits act. This implication may be demonstrated as follows.

In affirming the real distinction between matter and form, which is a real distinction between potency and act,  it necessarily follows that matter limits form, or as St. Thomas explicates, potency limits act: if act and potency are composed and yet act is perfection and potency is imperfection, then potency must of necessity limit act, since, in composing with act, it confers its imperfection on the composite being such that the composite being is not pure act but act admixed with the imperfection of potency.  Hence the doctrine of limitation follows from the real distinction. Thus, the Lublin Dominican Thomist Krapiec OP,


“Aristotle himself already observed that beings are found in two states, perfect and imperfect, and that perfection is connected with potency.  A thing is perfect insofar as it is act and insofar as it is potency.  Consequently, all imperfection is connected with one kind of potency or another…If Aristotle is correct in identifying perfection with act and imperfection with potency, then the cause of whatever kind of imperfection we encounter in beings will always be potency, since apart from act and potency (analogically understood) there is no third constitutive element of being.”[18]




Let me further suggest that it would be a red herring and inconsequential to speculate on the original intentions of Aristotle in positing the real distinction between form and matter.  It may perhaps be true, and indeed we may even concede to it, that as Fr. Clarke SJ says, the genuine meaning and purpose of the act and potency composition in Aristotle is “as a function of the problem of change”.[19]  - as if this would absolve Aristotle of the doctrine of limitation. Quite the contrary. Since this same principle of the real distinction must necessarily be presupposed in the fruitful analysis of change of beings as composite substances of matter and form and therefore follows from it, then whatever further follows from it is the happy fault of the intent to solve the mystery of change.   Hence,


“The real distinction between prime matter and form is derived therefore from the distinction between potency and act.  This distinction is necessary for the explanation of substantial change…Since matter endures under the form that it receives, which it can lose, it follows that, for instance, the form of the lion is susceptible of unlimited participation in the matter which limits it, so as to constitute with it a composite that is generated and corruptible.”[20]


In other words, since the solution for the problem of change presupposes the real distinction, it follows that the doctrine of limitation is simply a corollary of the Aristotelian solution to the problem of change, without which doctrine of limitation Aristotle could not account for the existence of change as a middle solution between Permanides and Heraclitus.


Or:     Aristotelian Solution to Change É Real Distinction É Doctrine of Limitation

          ~ Doctrine of Limitation É ~ Real Distinction Modus Tollens

          ~ Real Distinction É ~ Aristotelian  Solution to Change Modus Tollens


From this Fr. Garrigou-Lagrange OP then goes on to comment how for St. Thomas from this itself may be derived  the principle, “act is limited by potency”:


“[St. Thomas] remarks that the form is limited not only, and precisely in so far as it is a form of the sensible order, but also as act or perfection.  Every perfection, indeed, which is not limited by itself is so, in fact, by a certain capacity that it has for perfection or by the matter in as much as it is a potency. Hence the absolute universality of the principle, either in the sensible or suprasensible order, that “act as a perfection is limited only by the potency which is itself a certain capacity for perfection.”[21]


Having arrived at the more general principle, that “act is limited by potency”, St. Thomas then applies it to beings as composites of  essence and existence (esse) according to  its mode in the metaphysical order, which Aristotle could not do.   

And, that is why Fr. Garrigou-Lagrange OP writes - without misinterpretation - “All this is explained at length by Aristotle in the first two books of the Physics; the truth of this principle, that act is limited…by potency,  is there most clearly demonstrated, at least as regards beings of the sensitive order.”[22]  That is to say, every being, for insofar as it is a being, because of the fact of change, is composed of really distinct act and potency. And further,  we may ascribe any imperfection only to the potency and not the act. 

Though a demand for an explicit statement on this by Aristotle on the part of Fr. Clarke SJ is not an unjust request, it seems to me much more than a leap of faith to conclude that Aristotle did not teach it simply from the fact that he did not explicitly make mention of it when on the other hand there is abundant proof that it follows strictly from his principal ideas. Since the Philosopher divided substances into act and potency as really distinct, then, there is no mistake that his system implied the limitation of act by potency, as we have seen above.  Infact, the sequence is so immediate that it comes to us as no surprise thus when Fr. Garrigou-Lagrange OP asks the question: Does the principle, “act is limited only by potency” admit demonstration? he himself explains,


“In answer, we say that it cannot be proved by a direct and illative process of reasoning, because we are not dealing here with a conclusion properly so called, but truly with a first principle, which is self evident (per se notum), on condition that we correctly interpret the meaning of its terms, subject and predicate. Nevertheless the explanation of its terms can be expressed in a form of reasoning, not illative, but explicative, containing at the same time an indirect demonstration, which shows that the denial of the principle leads to absurdity.  This explicative argument may be formulated as here follows.


An act, a perfection, which in its own order is of itself unlimited (for example, existence or wisdom or love) cannot in fact be limited except by something else not of its own order, something which is related to that perfection and gives the reason for that limitation.  Now, nothing else can be assigned as limiting  that act, that perfection, except the real potency, the capacity for receiving the act, that perfection.  Therefore that act, as perfection of itself unlimited, cannot be limited except by the potency which receives that act.”[23]


By understanding the terms, act and potency, we quickly see that potency limits the act.  There is no other possibility.  For there is either act or potency. Could it be act limiting act, as Suarez even suggests?[24]  No, because act is perfection, and to say that perfection becomes imperfection of itself in the same order is without sufficient reason:


“Act of itself and in the order in which it is act is not limited, for act as such is “of itself” a perfection.  If therefore, being an act is synonymous with being a perfection, and if limitation is an imperfection, then act of itself cannot cause limitation, for a perfection of itself - by definition - cannot be an imperfection.  If, then, we affirm different types of limited beings in reality, their limitation is not explained by act but by another inner ontic element, an element that also constitutes a given being, namely potency.”[25]





It is clear, then, that the doctrine of limitation is definitely latent in Aristotle's thought, as a corollary of his solution to change, as we saw above.  To assert that Aristotle taught it is hardly a “misinterpretation”, strictly speaking. We thus clear Fr. Garrigou-Lagrange OP of this charge, and maintain the undeniable Aristotelian ascendency to the Doctrine of Limitation, regardless of the Neoplatonic elements that St. Thomas integrated with it.  Indeed perhaps even that, that is, the Neoplatonism, is set in an Aristotelian ground. As Fr. Krapiec OP writes,  


Why are all beings not pure perfection?  Why does perfection in beings exist to a limited, partial degree?  The questions have meaning not only in the context of Eleatic or Platonic thought, but also in the context of Aristotle’s thought.  The fact that Aristotle did not ask them is no reason for assuming they cannot be asked in the context of his thought, and, in fact, they were later asked.[26]


[1] Reginald Garrigou-Lagrange OP, Reality: A Synthesis of Thomistic Thought,  1950: Herder (USA), pp.43-44; quoted in W. Norris Clarke SJ, “The Limitation of Act by Potency” in Explorations in Metaphysics: Being-God-Person. 1994: UNDP (USA). p. 67.

[2] W. Norris Clarke SJ, op. cit.  pp. 67-68

[3] Ibid., pp. 68-69

[4] Ibid., p. 82

[5] Reginald Garrigou-Lagrange OP, op cit., p.44

[6] Reginald Garrigou-Lagrange OP, God: His Existence and His Nature - A Thomistic Solution of Certain Agnostic Antinomies. Vol. II., 1946: Herder (USA), p. 551.  

[7] Reginald Garrigou-Lagrange OP, Reality, op. cit., p. 41.

[8] Ibid., p. 43

[9] W. Norris Clarke SJ, op. cit., p. 74

[10] Cajetan, Thomas de Vio OP, In De Ente et Essentia d. Thomas Aquinatis. Lottie H. Kendzierski; Francis C. Wade SJ (transl.) 1964:Marquette University Press (USA). p. 258

[11] Ibid. 

[12] Ibid., p. 258-259

[13] Reginald Garrigou-Lagrange OP, God, op. cit.,  p. 548

[14] Aristotle, Physics, I, VIII, in A New Aristotle Reader, J.L. Ackrill (ed.), 1989: Princeton University Press. (USA), p. 91-92.

[15] St. Thomas Aquinas, Commentary on Aristotle’s Physics, Lecture 14, 126-127. 1963: Routledge and Kegan Paul (London), p. 60

[16] Ibid.,  Lecture 14, 127.

[17] Reginald Garrogiu-Lagrange OP, God, op. cit.,  p. 552

[18] M. A. Krapiec OP, Metaphysics: An Outline of the History of Being (Catholic Thought from Lublin Series, Vol. 2). 1991: Peter Lang (USA) p. 254.

[19] W. Norris Clarke SJ., op. cit., p. 74

[20] Reginald Garrigou-Lagrange OP, God, op. cit., p.552

[21]Ibid., p. 553.

[22] Ibid., p. 552.

[23] Reginald Garrigou-Lagrange OP, Reality, op. cit., p. 45

[24] C.f. Disp. Met., XXX, sect. 2, no. 18; XXXI, sect. 13, no. 14. C.f. Reginald Garrigou-Lagrange OP, Reality, op. cit., p.45

[25] M. A, Krapiec, op. cit., p. 256

[26] Ibid., p. 256