Chapter 5: Act And Potency

The doctrine on act and potency is the soul of Aristotelian philosophy, deepened and developed by St. Thomas. [147] .

According to this philosophy, all corporeal beings, even all finite beings, are composed of potency and act, at least of essence and existence, of an essence which can exist, which limits existence, and of an existence which actualizes this essence. God alone is pure act, because His essence is identified with His existence. He alone is Being itself, eternally subsistent.

The great commentators often note that the definition of potency determines the Thomistic synthesis. When potency is conceived as really distinct from all act, even the least imperfect, then we have the Thomistic position. If, on the other hand, potency is conceived as an imperfect act, then we have the position of some Scholastics, in particular of Suarez, and especially of Leibnitz, for whom potency is a force, a virtual act, merely impeded in its activity, as, for example, in the restrained force of a spring.

This conceptual difference in the primordial division of created being into potency and act has far-reaching consequences, which it is our task to pursue.

Many authors of manuals of philosophy ignore this divergence and give hardly more than nominal definitions of potency and act. They offer us the accepted axioms, but they do not make clear why it is necessary to admit potency as a reality between absolute nothing and actually existing being. Nor do they show how and wherein real potency is distinguished, on the one hand, from privation and simple possibility, and on the other from even the most imperfect act.

We are now to insist on this point, and then proceed to show what consequences follow, both in the order of being and in the order of operation. [148] .

Article One: Potency Really Distinct From Act

According to Aristotle, [149] real distinction between potency and act is absolutely necessary if, granting the multiplied facts of motion and mutation in the sense world, facts affirmed by experience, we are to reconcile these facts with the principle of contradiction or identity. Here Aristotle [150] steers between Parmenides, who denies the reality of motion, and Heraclitus, who makes motion and change the one reality.

Parmenides has two arguments. The first runs thus: [151] If a thing arrives at existence it comes either from being or from nothing. Now it cannot come from being (statue from existing statue). Still less can it come from nothing. Therefore all becoming is impossible. This argument is based on the principle of contradiction or identity, which Parmenides thus formulates: Being is, non-being is not; you will never get beyond this thought.

Multiplicity of beings, he argues again from the same principle, is likewise impossible. Being, he says, cannot be limited, diversified, and multiplied by its own homogeneous self, but only by something else. Now that which is other than being is non-being, and non-being is not, is nothing. Being remains eternally what it is, absolutely one, identical with itself, immutable. Limited, finite beings are simply an illusion. Thus Parmenides ends in a monism absolutely static which absorbs the world in God.

Heraclitus is at the opposite pole. Everything is in motion, in process of becoming, and the opposition of being to non-being is an opposition purely abstract, even merely a matter of words. For, he argues, in the process of becoming, which is its own sufficient reason, being and non-being are dynamically identified. That which is in the process of becoming is already, and nevertheless is not yet. Hence, for Heraclitus, the principle of contradiction is not a law of being, not even of the intelligence. It is a mere law of speech, to avoid self-contradiction. Universal becoming is to itself sufficient reason, it has no need of a first cause or of a last end.

Thus Heraclitus, like Parmenides, ends in pantheism. But, whereas the pantheism of Parmenides is static, an absorption of the world into God, the pantheism of Heraclitus is evolutionist, and ultimately atheistic, for it tends to absorb God into the world. Cosmic evolution is self-creative. God, too, is forever in the process of becoming, hence will never be God.

Aristotle, against Heraclitus, holds that the principle of contradiction or of identity is a law, not merely of the inferior reason and of speech, but of the higher intelligence, and primarily of objective reality. [152] Then he turns to solve the arguments of Parmenides.

Plato, attempting an answer to Parmenides, had admitted, on the one side, an unchangeable world of intelligible ideas, and on the other, a sense world in perpetual movement. To explain this movement, he held that matter, always transformable, is a medium between being and nothing, is "non-being which somehow exists." Thus, as he said, he held his hand on the formula of Parmenides, by affirming that non-being still in some way is. [153] Confusedly, we may say, he prepared the Aristotelian solution, deepened by St. Thomas.

Aristotle's solution, more clear and profound than Plato's, rests on his distinction of potency from act, a distinction his thought could not escape. [154] .

In fact, that which is in process of becoming cannot arise from an actual being, which already exists. The statue, in process of becoming, does not come from the statue which already exists. But the thing in process of becoming was at first there in potency, and hence arises from unterminated being, from real and objective potency, which is thus a medium between the existing being and mere nothing. Thus the statue, while in process, comes from the wood, considered not as existing wood, but as sculptilis. Further, the statue, after completion, is composed of wood and the form received from the sculptor, which form can give place to another. The plant is composed of matter and specific (substantial) form (oak or beech): and the animal likewise (lion, deer).

The reality of potency is thus a necessary prerequisite if we are to harmonize the data of sense (e. g.: multiplicity and mutation) with the principle of contradiction or of identity, with the fundamental laws, that is, of reality and of thought. That which begins, since it cannot come either from actuality or from nothing, must come from a reality as yet undetermined, but determinable, from a subject that is transformable, as is the prime matter in all bodies, or as is second matter, in wood, say, or sand, or marble, or seed. In the works above cited St. Thomas gives explicit development to this conception of the Stagirite. Let us briefly note these clarifications.

But now this determinableness, transformableness: what is it positively? What is this real, objective potency, presupposed to motion, to mutation, to transformation? It is a real capacity to receive a definite, determined form, the form, say, of the statue, a capacity which is not in air or water, but is in wood, or marble, or sand. This capacity to become a statue is the statue in potency.

Here lies Aristotle's superiority to Plato. Plato speaks of "non-being which in some way is." He seems to be thinking of privation or simple possibility, or of an imperfect actuality. His conception of matter, and of non-being in general, remains quite obscure when compared with the Aristotelian concept of potency, passive or active.

St. Thomas excels in explaining this distinction, just now noted, between passive potency and active potency. Real passive potency is not simple possibility. Simple possibility is prerequired and suffices for creation ex nihilo. But it does not suffice as prerequisite for motion, change, mutation. Mutation presupposes a real subject, determinable, transformable, mutable, whereas creation is the production of the entire created being, without any presupposed real potency. [158] Now, since active potency, active power, must be greater in proportion to its passive correlative, it follows that when passive potency is reduced to zero, the active potency must be infinite. In other words, the most universal of effects, the being of all things, cannot be produced except by the most universal of all causes, that is, by the Supreme Being. [159] .

Real potency admitted, we have against Parmenides the explanation, not merely of mutation and becoming, but also of multiplicity. Form, of itself unlimited, is limited by the 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. And from this viewpoint, as long as that which was in potency is now in act, this real potency remains beneath the act. The wood, by receiving the statue-form, limits and holds this form and can even lose it and receive another form. The form of Apollo, as long as it remains in this particular piece of wood, is thereby limited, individualized, and as such, irreproducible. But a similar form can be reproduced in another portion of matter and that in indefinitum.

Article Two: Act Limited By Potency

Act, being completion, perfection, is not potency, which is the capacity to receive perfection: and act, perfection, is limited only by the potency which is its recipient. This truth is thus expressed in two texts of St. Thomas: "Form, even the lowest material form, if it be supposed, either really or mentally, separate from matter, is specifically one and one only. If whiteness, e. g.: be understood as apart from any subject of whiteness, it becomes impossible to suppose many whitenesses." [160] Again: "Things which agree in species and differ by number, agree in form and differ only in matter. Hence since the angels are not composed of matter and form, it is impossible to have two angels agreeing in species." [161] .

This doctrine is embodied in the second of the twenty-four theses, approved by the Sacred Congregation of Studies in 1914. That thesis runs thus: "Act, perfection, is limited only by potency, which is the capability of receiving perfection. Hence, in an order of pure act, only one unlimited act can exist. But where act is limited and multiplied, there act enters into real composition with potency." [162] .

From this principle, upheld by St. Thomas and his entire school, follow many consequences, both in the order of being and in the order of activity, since activity is proportioned to the agent's mode of being.

Article Three

First we will indicate, rising from lower to higher, the consequences in the order of being.

a) Matter is not form; it is really distinct from form. Let us look attentively at substantial mutation. We take two instances. First, a lion is burned, and there remain only ashes and bones. Secondly, food, by assimilative, digestive power, is changed into human flesh. These substantial mutations necessarily presuppose in the thing to be changed a subject capable of a new form but in no way as yet determined to that form, because, if it had already some such determination, that determination would have to be a substance (like air or water): and the mutations in question would no longer be substantial, but only accidental.

The subject of these mutations, therefore, must be purely potential, pure potency. Prime matter is not combustible, not "chiselable," and yet is really determinable, always transformable. This pure potency, this simple, real capacity, to receive a new substantial form, is not mere nothing (from nothing, nothing comes) ; nor is it mere privation of the form to come; nor is it something substantial already determined. It is not, says St. Thomas, [163] substance or quality or quantity or anything like these. Nor is it the beginning (inchoatio) of the form to come. It is not an imperfect act. The wood which can be carved is not yet, as such, the beginning of the statue-form. the imperfect act is already motion toward the form. It is not the potency prerequired before motion can begin.

This capacity to receive a substantial form is therefore a reality, a real potency, which is not an actuality. It is not the substantial form, being opposed to it, as the determinable, the transformable, is opposed to its content. Now, if, in reality, antecedently to any act of our mind, matter, pure potency, is not the substantial form, then it is really distinct from form. Rather, it is separable from form, for it can lose the form it has received, and receive another though it cannot exist deprived of all form. Corruption of one form involves necessarily the generation of another form. [164] .

From the distinction, then, of potency from act arises between prime matter and form that distinction required to explain substantial mutation. Consequently prime matter has no existence of its own. Having no actuality of itself, it exists only by the existence of the composite. Thomas says: "Matter of itself has neither existence nor cognoscibility " [165] .

In this same manner Aquinas, after Aristotle, explains the multiplication of substantial form, since matter remains under form, limits that form, and can lose that form. The 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.

Aristotle already taught this doctrine. In the first two books of his Physica he shows with admirable clearness the 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. 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 thus no longer multipliable, though it can be multiplied in other portions of wax or marble. [166] .

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.

b) Created essence is not its own existence, but really distinguished from that existence. The reason, says St. Thomas, why the substantial, specific form is limited in sense objects (e. g.: lion) lies precisely in this: Form, act, perfection, precisely by being received into a really containing capacity, is thereby necessarily limited (made captive) by that container. Under this formula, the principle holds good even in the supersense order: Act, he says, being perfection, can be limited only by the potency, the capacity which receives that perfection. [167] Now, he continues, existence is actuality, even the ultimate actuality. [168] And he develops this thought as follows: "Existence is the most perfect of realities. It is everywhere the ultimate actuality, since nothing has actuality except as it is. Hence existence is the actuality of all things, even of forms themselves. Hence existence is never related as receiver is related to content, but rather as content to receiver. When I speak of the existence of a man, say, or of a horse, or of anything else whatever, that existence is in the order of form, not of matter. It is the received perfection, not the subject which receives existence." [169] .

Further, since existence (esse) is of itself unlimited, it is limited in fact only by the potency into which it is received, that is, by the finite essence capable of existence. By opposition, then "as the divine existence (God's existence) is not a received existence, but existence itself, subsistent, independent existence, it is clear that God is infinitely and supremely perfect." [170] Consequently God is really and essentially distinct from the world of finite things. [171] .

This doctrine is affirmed by the first of the twenty-four Thomistic theses: Potency and act divide being in such fashion that everything which exists is either pure act, or then is necessarily composed of potency and act, as of two primary and intrinsic principles. [172] .

For Suarez, on the contrary, everything that is, even prime matter, is of itself in act though it may be in potency to something else. Since he does not conceive potency [173] as the simple capacity of perfection, he denies the universality of the principle: act is limited only by potency. Here are his words: "Act is perhaps limited by itself, or by the agent which produces the act." [174] .

The question arises: Does this principle, "act is limited only by potency," admit demonstration? 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 these terms can be expressed in a form of reasoning, not illative, but explicative, containing at the same time an indirect demonstration, which shows that 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 that act, that perfection. Therefore that act, as perfection of itself unlimited, cannot be limited except by the potency which receives that act.

The major proposition of this explicative argument is evident. If, indeed, the act (of existence, of wisdom, of love) is not of itself limited, it cannot in fact be limited except by something extraneous to itself, something which gives the reason for the limitation. Thus the existence of the stone (or plant, animal, man) is limited by its nature, by its essence, which is susceptible of existence (quid capax existendi). Essence, nature, gives the reason of limitation, because it is intrinsically related to existence, it is a limited capability of existence. Similarly wisdom in man is limited by the limited capacity of his intelligence, and love by the limited capacity of his loving power.

Nor is the minor proposition of the argument less certain. If you would explain how an act, a perfection, of itself unlimited is in point of fact limited, it is not sufficient, pace Suarez, to appeal to the agent which produces that act, because the agent is an extrinsic cause, whereas we are concerned with finding the reason for this act's intrinsic limitation, the reason why the being, the existence, of the stone, say (or of the plant, the animal, the man): remains limited, even though the notion of being, of existence implies no limit, much less of different limits. Just as the sculptor cannot make a statue of Apollo limited to a portion of space, unless there is a subject (wood, marble, sand) capable of receiving the form of that statue: so likewise the author of nature cannot produce the stone (or the plant, the animal, the man) unless there is a subject capable of receiving existence, and of limiting that existence according to the different capacities found in stone, plant, and animal.

Hence St. Thomas says: "God produces simultaneously existence and the subject which receives existence." [175] And again: "In the idea of a made thing lies the impossibility of its essence being its existence because subsistent, independent existence is not created existence." [176] .

Were this position not admitted, the argument of Parmenides, renewed by Spinoza, would be insoluble. Parmenides denied multiplicity in the sense world, because being cannot be limited, diversified, multiplied of itself, he says, but only by something other than itself, and the only thing other than being is non-being, is pure nothing.

To this argument our two teachers reply: Besides existence there is a real capacity which receives and limits existence. [177] This capacity, this recipient, which limits existence, is not nothing, is not privation, is not imperfect existence; it is real objective potency, really distinct from existence, just as the transformable wood remains under the statue figure it has received, just as prime matter remains under the substantial form, really distinct from that form which it can lose. As, antecedently to consideration by our mind, matter is not form, is opposed to form, as that which is transformable is opposed to that which informs, thus likewise the essence of the stone (the plant, the animal) is not its existence. Essence, as essence (quid capax existendi): does not contain actual existence, which is a predicate, not essential, but contingent. Nor does the idea of existence as such imply either limitation or diversity in limitation (as, say, between stone and plant).

To repeat: Finite essence is opposed to its existence as the perfectible to actualizing perfection, as the limit to the limited thing, as the container to the content. Antecedently to any thought of ours, this proposition is true: Finite essence is not its own existence. Now, if in an affirmative judgment, the verb "is" expresses real identity between subject and predicate, [178] then the negation denies this real identity and thus affirms real distinction.

How is this distinction to be perceived? Not by the senses, not by the imagination, but by the intellect, which penetrating more deeply (intus legit): sees that finite essence, as subject, does not contain existence, which is not an essential predicate, since it is contingent.

A wide difference separates this position from that which says: Being is the most simple of ideas, hence all that in any way exists is being in act, though it may often be in potency to something else. Thus prime matter is already imperfectly in act, and finite essence is also in act, and is not really distinct from its existence Thus Suarez. [179] .

A follower of Suarez, P. Descoqs, S. J.: writes thus concerning the first [180] of the twenty-four Thomistic theses: "Now if it is maintained that this thesis reproduces faithfully the teaching of Cajetan, and of subsequent authors inspired by Cajetan, I would certainly not demur. But however hard he tries, no one will show, and the chief commentators, however hard they have tried, have not been able to show, that the said teaching is found in the Master." [181] .

Must we then say that the Congregation of Studies was in error, when, in 1914, it approved as genuine expression of the doctrine of St. Thomas, both that first thesis here in question and the other theses derived from that first? Is it true, as the article just cited maintains, [182] that St. Thomas never said that, in every created substance there is, not merely a logical composition, but a real composition of two principles really distinct, one of these principles, essence, subjective potency, being correlated to the other, existence, which is its act?

Now surely St. Thomas does say just this, and says it repeatedly. Beyond texts already cited, listen to the following passage: "Everything that is in the genus of substance is composed by a real composition, because, being substance, it is subsistent (independent) in its being. Hence its existence is something other than itself, otherwise it could not by its existence differ from other substances with which in essence it agrees, this condition being required in all things which are directly in the predicaments. Hence everything that is in the genus of substance is composed, at least of existence and essence (quod est)." [183] The beginning of this passage shows that the composition in question is not merely logical, but is real. Thus the passage says exactly what the first of the twenty-four theses says.

Let us hear another passage. "Just as every act (existence) is related to the subject in which it is, just so is every duration related to its now. That act however, that existence, which is measured by time, differs from its subject both in reality (secundum rem): because the movable thing is not motion, and in succession, because the substance of the movable thing is permanent, not successive. But that act, which is measured by aevum, namely, the existence of the thing which is aeviternal, differs from its subject in reality, but not in succession, because both subject and existence are each without succession. Thus we understand the difference between aevum and its now. But that existence which is measured by eternity is in reality identified with its subject, and differs from it only by way of thought." [184] .

The first text just quoted says that in every predicamental substance there is a real composition between potency and act. The second text says that in substances measured by aevum (the angels) there is real distinction between existence and its subject. This is exactly the doctrine expressed by the first of the twenty-four theses.

We may add one more quotation from St. Thomas: "Hence each created substance is composed of potency and act, that is, of subject and existence, as Boethius says, [185] just as the white thing is composed of white thing and whiteness." [186] Now the saint certainly holds that there is real distinction between the white subject and its whiteness, between substance and accident. In both cases then, between substance and accident, and between essence and existence, we have a distinction which is not merely logical, subsequent to our way of thinking, but real, an expression of objective reality.

Antecedently to our way of thinking, so we may summarize Aristotle, matter is not the substantial form, and matter and form are two distinct intrinsic causes. St. Thomas supplements Aristotle with this remark: In every created being there is a real composition of potency and act, at least of essence and existence. [187] Were it otherwise, the argument of Parmenides against multiplicity of beings would remain insoluble. As the form is multiplied by the diverse portions of matter into which it is received, just so is existence (esse) multiplied by the diverse essences, or better, diverse subjects, [188] into which it is received.

To realize this truth you have but to read one chapter in Contra Gentes. [189] The composition there defended is not at all merely logical composition (of genus and differentia specifica, included in the definition of pure spirits): but rather a real composition: essence is not really identified with existence, which only contingently belongs to essence.

Throughout his works, St. Thomas continually affirms that God alone is pure act, that in Him alone is essence identified with existence. [190] In this unvaried proposition he sees the deepest foundation of distinction between uncreated being and created being. [191] Texts like these could be endlessly multiplied. See Del Prado, [192] where you will find them in abundance.

The first of the twenty-four theses, then, belongs to St. Thomas. In defending that thesis we are not pursuing a false scent, a false intellectual direction, on one of the most important points of philosophy, namely, the real and essential distinction between God and the creature, between pure act, sovereignly simple and immutable, and the creature always composed and changing. [193] .

On this point, it is clear, there is a very notable difference between St. Thomas and Suarez, who in some measure returns to the position of Duns Scotus. Now this difference rests on a difference still more fundamental, namely, a difference in the very idea of being (ens): which ontology deals with before it deals with the divisions of being. To this question we now turn.

The Idea Of Being

Being, for St. Thomas, [194] is a notion, not univocal but analogous, since otherwise it could not be divided and diversified. A univocal idea (e. g.: genus) is diversified by differences extrinsic to genus (animality, e. g.: by specific animal differences). Now, nothing is extrinsic to being (ens). Here Parmenides enters. Being, he says, cannot be something other than being, and the only other thing than being is nothing, is non-being, and non-being is not. St. Thomas replies: "Parmenides and his followers were deceived in this: They used the word being (ens) as if it were univocal, one in idea and nature, as if it were a genus. This is an impossible position. Being (ens) is not a genus, since it is found in things generically diversified." [195] .

Duns Scotus [196] returns in a manner to the position of Parmenides, that being is a univocal notion. Suarez, [197] seeking a middle way between Aquinas and Scotus, maintains that the objective concept of being (ens) is simply one (simpliciter unus): and that consequently everything that is in any manner (e. g.: matter and essence) is being in act (ens in actu). This viewpoint granted, we can no longer conceive pure potency. It would be extra ens, hence, simply nothing. The Aristotelian notion of real potency (medium between actuality and nothing) disappears, and the argument of Parmenides is insoluble.

We understand now why, shortly after the Council of Trent, a Thomist, Reginaldus, O. P.: [198] formulated as follows the three principles of St. Thomas:

Metaphysical Idea Of God

From this initial ontological divergence we have noted between St. Thomas and Suarez there arises another divergence, this time at the summit of metaphysics. Thomists maintain that the supreme truth of Christian philosophy is the following: In God alone are essence and existence identified. Now this is denied by those who refuse to admit the real distinction between created essence and existence.

According to Thomists this supreme truth is the terminus, the goal, of the ascending road which rises from the sense world to God, and the point of departure on the descending road, which deduces the attributes of God and determines the relation between God and the world. [199] .

From this supreme truth, that God alone is His own existence, follow, according to Thomists, many other truths, formulated in the twenty-four Thomistic theses. We will deal with this problem later on, when we come to examine the structure of the theological treatise, De Deo uno. Here we but note the chief truths thus derived.

Consequences Of This Distinction

God, since He is subsisting and unreceived being, is infinite in perfection. [200] In Him there are no accidents, because existence is the ultimate actuality, hence cannot be further actualized and determined. [201] Consequently He is thought itself, wisdom itself, [202] love itself. [203] .

Further, concerning God's relations to creatures we have many other consequences of the real distinction between act and potency. Many positions which we have already met on the ascending road now reappear, seen as we follow the road descending from on high. There cannot be, for example, two angels of the same species, for each angel is pure form, irreceivable in matter. [204] The rational soul is the one sole substantial form of the human composite, since otherwise man would not be simply a natural, substantial unity, [205] but merely one per accidens (as is, e. g.: the unity between material substance and the accident of quantity). For substantial unity cannot arise from actuality plus actuality, but only from its own characteristic potency and its own characteristic actuality. [206] Consequently the human composite has but one sole existence (see the sixteenth of the twenty-four Thomistic theses). Similarly, in every material substance there is but one existence, since neither matter nor form has an existence of its own; they are not id quod est, but id quo [207] (see the ninth of the twenty-four). The principle of individuation, which distinguishes, e. g.: two perfectly similar drops of water, is matter signed with quantity, the matter, that is, into which the substantial form of water has been received, but that matter as proportioned to this quantity (proper to this drop) rather than to another quantity (proper to another drop). [208] .

Again, prime matter cannot exist except under some form, for that would be "being in actuality without act, a contradiction in terms." [209] Prime matter is not "that which is (id quod est): " but "that by which a thing is material, and hence limited." [210] Consequently "matter of itself has no existence, and no cognoscibility." [211] Matter, namely, is knowable only by its relation to form, by its capacity to receive form. The form of sense things, on the contrary, being distinct from matter, is of itself and directly knowable in potency. [212] Here is the reason for the objectivity of our intellectual knowledge of sense objects. Here also the reason why immateriality is the root of both intelligibility and intellectuality. [213] .

Article Four

We come now to the applications of our principle in the order of action, operation, which follows the order of being. [214] Here we will briefly indicate the chief consequences, on which we must later dwell more at length.

Powers, faculties, habitudes differ specifically, not of themselves, but by the formal object, the act to which they are proportioned. [215] Consequently the soul faculties are really distinct from the soul, and each is really distinct from all others. [216] No sense faculty can grasp the proper object of the intelligence, nor sense appetite the proper object of the will. [217] .

"Whatever is moved (changed) is moved by something else." [218] This principle is derived from the real distinction between potency and act. Nothing can pass from potency to act except by a being already in act, otherwise the more would come from the less. In this principle is founded the proof from motion, from change, for God's existence. [219] Now, for Suarez, this principle is uncertain, for he says, "there are many things which, by virtual acts, are seen to move and reduce themselves to formal acts, as may be seen in appetite or will." [220] Against this position we must note that if our will is not its own operation, its own act of willing, if "God alone is His own will, as He is His own act of existence, and His own act of knowing," then it follows that our will is only a potency, only a capability of willing, and cannot consequently be reduced to act except by divine motion. Were it otherwise, the more would come from the less, the more perfect from the less perfect, contrary to the principle of causality. [221] St. Thomas speaks universally: "However perfect you conceive any created nature, corporeal or spiritual, it cannot proceed to its act unless it is moved thereto by God." [222] .

The next consequence deals with causal subordination. In a series of causes which are subordinated necessarily (per se, not per accidens): there is no infinite regress; we must reach a supreme and highest cause, without which there would be no activity of intermediate causes, and no effect. [223] .

We are dealing with necessary subordination. In accidental subordination, regress in infinitum is not an absurdity. In human lineage, for example, the generative act of the father depends, not necessarily, but accidentally, on the grandfather, who may be dead. But such infinite regress is absurd in a series necessarily subordinated, as, for example, in the following: "the moon is attracted by the earth, the earth by the sun, the sun by another center, and thus to infinity. Such regress, we must say, is absurd. If there is no first center of attraction, here and now in operation, then there would be no attraction anywhere. Without an actually operating spring the clock simply stops. All its wheels, even were they infinite in number, cause no effect." [224] .

This position Suarez denies. He speaks thus: "In causes necessarily (per se) subordinated, it is no absurdity to say that these causes, though they be infinite in number, can nevertheless operate simultaneously." [225] Consequently Suarez [226] denies the demonstrative validity of the proofs offered by St. Thomas for God's existence. He explains his reason for departing from the Angelic Doctor. He substitutes for divine motion what he calls "simultaneous cooperation." [227] The First Cause, he says, does not bring the intermediate second cause to its act, is not the cause of its activity. In a series of subordinated causes, higher causes have influence, not on lower causes, but only on their common effect. All the causes are but partial causes, influencing not the other causes, but the effect only. [228] All the causes are coordinated rather than subordinated. Hence the term: simultaneous concursus, illustrated in two men drawing a boat. [229] .

This view of Suarez is found also in Molina. Molina says: "When causes are subordinated, it is not necessary that the superior cause moves the inferior cause, even though the two causes be essentially subordinated and depend on each other in producing a common effect. It suffices if each has immediate influence on the effect." [230] This position of Molina supposes that active potency can, without impulse from a higher cause, reduce itself to act. But he confuses active potency with virtual act, which of itself leads to complete act. Now, since a virtual act is more perfect than potency, we have again, contrary to the principle of causality, the more perfect issuing from the less perfect.

St. Thomas and his school maintain this principle: No created cause is its own existence, or its own activity, hence can never act without divine premotion. In this principle lies the heart of the proofs, by way of causality, for God's existence. [231] .

All these consequences, to repeat, follow from the real distinction between potency and act. From it proceed: the real distinction between matter and form, the real distinction between finite essence and existence, the real distinction between active potency and its operation.

In the supernatural order we find still another consequence from the idea of potency, namely, obediential potency, that is, the aptitude of created nature, either to receive a supernatural gift or to be elevated to produce a supernatural effect. This potency St. Thomas conceives as the nature itself, of the soul, say, as far as that nature is suited for elevation to a superior order. This suitableness means no more than non-repugnance, since God can do in us anything that is not self-contradictory. [232] .

For Suarez, [233] on the contrary, this obediential potency, which he regards as an imperfect act, is rather an active potency, as if the vitality of our supernatural acts were natural, instead of being a new, supernatural life. Thomists answer Suarez thus: An obediential potency, if active, would be natural, as being a property of our nature, and simultaneously supernatural, as being proportioned to an object formally supernatural. [234] .

A last important consequence, again in the supernatural order, of the real distinction between potency and act, between essence and existence, runs as follows: In Christ there is, for both natures, the divine and the human, one sole existence, the existence, namely, of the Word who has assumed human nature. [235] Suarez, on the contrary, who denies real distinction between created essence and its existence, has to admit two existences in Christ. This position reduces notably the intimacy of the hypostatic union.

Such then are the principal irradiations of the Aristotelian distinction between potency and act. Real, objective potency is not act, however imperfect. But it is essentially proportioned to act. [236] Next come consequences in the four kinds of causes, with the absurdity, in necessary causal subordination, of regress in infinitum, either in efficient causality or in final causality. Culmination of these consequences is the existence of God, pure act, at the summit of all existence, since the more cannot come from the less, and in the giver there is more than in the receiver. The first cause, therefore, of all things cannot be something that is not as yet, but is still in process of becoming, even if you call that process self-creating evolution. The first cause is act, existing from all eternity, is self-subsisting Being, in whom alone essence and existence are identified. Already here we see that nothing, absolutely no reality, can exist without Him, without depending on Him, without a relation to Him of causal dependence on Him. Our free act of will, being a reality, has to Him the same relation of causal dependence, and is thereby, as we shall see, not destroyed, but on the contrary, made an actual reality. [237] .

This metaphysical synthesis, as elaborated by Aquinas, while far more perfect than the doctrine explicitly taught by Aristotle, is nevertheless, philosophically speaking, merely the full development of that doctrine. In Aristotle the doctrine is still a child. In Aquinas it has grown to full age. Now this progress, intrinsically philosophic, was not carried on without the extrinsic concurrence of divine revelation. Revelation, for St. Thomas, was not, in philosophy, a principle of demonstration. But it was a guiding star. The revealed doctrine of free creation ex nihilo was, in particular, a precious guide. But under this continued extrinsic guidance, philosophy, metaphysics, guarded its own formal object, to which it is by nature proportioned, namely, being as being, known in the minor sense world. By this formal object, metaphysics remains specifically distinct from theology, which has its own distinctive formal object, namely, God as He is in Himself, [238] God in His own inner life, known only by divine revelation. And here we can already foresee what harmony, in the mind of St. Thomas, unites these two syntheses, a harmony wherein metaphysics gladly becomes the subordinated instrument of theology. [239] .