Commentaria in Summam contra Gentiles, Liber I

After Saint Thomas has determined concerning the divine goodness, he now determines concerning its unity ¹. Here it must be noted that, in determining the divine perfections, Saint Thomas does not follow the order that belongs to those perfections in themselves, but the order of dependence according to the knowledge handed down by him. For since from the fact that we know God to be perfect there results the knowledge that He is good—because each thing is good insofar as it is perfect—therefore after the determination concerning perfection he at once determined concerning goodness, even though goodness is naturally posterior to unity. Similarly, since from the fact that God is known to be the highest good ² it is at once had that He is one, therefore after goodness he determines concerning unity.

I. On this, therefore, he proposes this conclusion: There is only one God.

It is proved, however, in several ways. And first thus: God is supremely good. Therefore He is only one. — The consequence is proved: because what is said by way of superabundance belongs to one alone.

It must be noted that it is not at all the same thing for something to be said by superabundance and to be said superlatively. For something can be said superlatively both by excess over other things and by the negation of what exceeds: as hottest either because it surpasses all hot things, or because nothing is hotter than itself. To be said by superabundance, however, is to surpass all things. And this belongs to one alone. For if this belonged to several, one would not surpass the other, and thus neither would be said to be highest by superabundance over all: and so a contradiction would be implied. If, therefore, God is the highest good as surpassing all goods, it is impossible that there be two gods: for then there would be two highest goods.

II. Second. If there were several gods, there would be several perfect things lacking nothing. But this is impossible. Therefore, etc. — The inference is proved: because, as was shown above, God is wholly perfect, lacking no perfection. — The falsity of the consequent is proved: because if no perfection were lacking to any of them, nor any imperfection mixed into any of them, which is required for something to be simply perfect, there would be nothing in which they could be distinguished from one another.

It must be noted that, if there were something in one god by which he would be distinguished from another god, it would be necessary for something to exist in the one that was not in the other. That thing, then, would either be some perfection or some imperfection. If a perfection, then that other god would lack some perfection: which is wholly repugnant to the perfect. If an imperfection, then there would be in God some imperfection: which likewise does not befit what is simply and wholly perfect. For this reason Saint Thomas argues well that, if neither of them lacks any perfection and no imperfection is mixed into either, there will be nothing in which they are distinguished from one another. — It might perhaps be said that each would possess every perfection of the other according to species, though not according to number. But this is nothing. For even if they were distinct only in number, there would have to be in the one something beyond the nature of the species, as will be shown below ³, by which he would be distinguished from the other.

III. Third. What is sufficiently done by one thing posited is better done by one than by many. But the order of things is as good as it can possibly be: for the power of the first agent does not fall short of the power that exists in things toward perfection. And by one principle all things are sufficiently completed. Therefore, etc.

Concerning that proposition, The order of things is as good as it can possibly be, it must be known, from the teaching of Saint Thomas, I Sent., d. xliv, a. 2, and Prima, q. xxv, a. 6, ad 3, that, given the things that now exist and with nothing changed in any way, the order of the universe cannot be better, because there is nothing disordered in the things or parts of the universe. God could, however, establish another order through the creation of other creatures, or through an accidental improvement of those same parts.

2. But concerning the proof of that proposition, namely that the power of the first agent is not lacking to the power which is in things for perfection, a doubt arises. For Saint Thomas seems to wish that whatever perfection can be, is in things. This, however, seems false. For many things do not attain the perfection to which they are in natural potency, on account of some impediment. — Likewise it is clear that not all things attain those perfections to which they are in obediential potency. Therefore, and so on.

It is said that St. Thomas, when he speaks of the order of the universe—and the order of the parts of the universe itself follows upon the essential perfection of things—when he says that the power of the first agent is not lacking to the power which is in things for their perfection, understands this of essential perfection or of what follows upon essence. For if God did not give to some thing all that pertains to its essence, it would not be the same thing: since the essences of things are like numbers, in which, as is said in VIII Metaph., text. 10 ⁴, with unity added or subtracted the species is varied. If also they did not have all that follows upon their essence, they would not be perfect according to their nature. — He does not, however, understand this of perfection arriving accidentally.

When, however, the first argument is made—that not all things attain the perfection to which they are in potency—it is said that this is false concerning substantial perfection or perfection that accompanies substance.

When it is argued secondly, that things do not follow all those ends for which they are in obediential potency: the reply is that the proposition is understood of the natural potency of a creature, not of its obediential potency.

IV. Fourth. The first motion is one and continuous. Therefore the first mover is one. — The consequence is proved. It is impossible that one continuous motion, governing individual things ⁵ should be from several movers. For if they moved simultaneously, then each would be an imperfect mover: which does not befit the first mover, since the perfect is prior to the imperfect. — But if they did not move simultaneously, each of them would at some time move and at some time not move. And thus there would not be one continuous and regular motion. First, because one continuous motion is from one mover: and therefore, if there were not always one mover, the motion would not be one. Second, because a mover that does not always move is found to move irregularly: as is evident in violent and natural motions, where the motion is sometimes faster, sometimes slower.

Note that this argument is directed against the philosophers who posit God as moving by necessity, and does not conclude simply. For someone could say that these movers move together not because of an imperfection of power, as if one could not move without another, but because of a concord of will. — Yet we could also say that it concludes simply. For, since superfluity is not to be posited, especially in the first principle, if one mover suffices of itself to cause motion, no other first mover is to be posited.

V. Fifth. All motions of a bodily creature are ordered to one first motion, beyond which there is no other first motion that is not reduced back to it. Therefore, beyond the spiritual substance which is the end of the first motion, there is none that is not reduced back to it. But by this name we understand God. Therefore, etc. — The consequence is proved. Because bodily substance is ordered to spiritual substance as to its good, to which it strives to assimilate itself: since that goodness is fuller, and everything that is desires the best as far as it is possible.

It must be noted that Saint Thomas wishes to argue from a comparison between the spiritual substances, which are the ends of motions, and the motions themselves of corporeal substances. And he intends to argue thus: such as is the order among the motions of bodies, such is the order among the spiritual substances, which are the ends of those motions. But among the motions of bodies there is only one first, to which all the others are reduced. Therefore also among the spiritual substances there is only one first, into which all the others are reduced. And this we call God. Therefore, etc. — The major premise is proved: because every corporeal substance is ordered to a spiritual one as to that which it intends to assimilate itself by its motion, as to a perfection and as that in which goodness is contained more fully.

2. But it seems that this argument does not prove its conclusion. For someone could say that, although there is only one first spiritual substance among those things which are the ends of motions, nevertheless there are many others which are not the ends of proximate motions, but are simply first.

It is said that St. Thomas puts forward this argument as taken from Aristotle, Physics VIII ⁶ and Metaphysics XII ⁷, where, after showing that the number of separate substances corresponds to the number of the motions of the heavenly bodies, he concludes, finally, that there is one chief principle. Hence this argument does not conclude simply, but is ad hominem against the Peripatetic.

VI. Sixth. Beyond this world there is no other world. Therefore there is one governor of all. — The consequence is proved. Because of all things ordered to one another, their order to one another is on account of an order to something one: just as the order of the parts of an army is on account of the ordering of the whole army to its commander. The reason for this is that diverse things cannot be united in some relation from their own natures, insofar as they are diverse; nor from several orderers, because those, as diverse, cannot intend one order; and thus the order would be accidental. But the order of the universe is not accidental, insofar as lower things are governed by higher ones: since it is always or for the most part so. Therefore there must be one first orderer and governor of all.

It must be noted here, as is held in the First Part, q. 11, a. 3, that what is one per se is the cause of unity, if it is total, in one order and in one genus of cause; and, if many things are the cause of one thing, this is only per accidens, that is, through something else, inasmuch as they are in some way one. Therefore, since the first being and ordainer is the most perfect and is per se, it is better that it be one than many. On account of this, since he said here that many things, as diverse, do not intend one order, he added that either the order of things will be per accidens, or it is necessary to reduce it to something one that orders all things to the end it intends: namely, because, if the order of things is posited as per se, and many things are not per se the cause of one order but through something else, inasmuch as they are one, they must be reduced to one principle which is the cause per se.

VII. Seventh. If there were several, there would necessarily be two. But this is impossible. Therefore, etc. — The falsity of the consequent is proved: because, since they would agree in the intention and quiddity of necessary esse, they would have to be distinguished by something added, either to one alone or to both. And thus either one or both would be composite, which is repugnant to that which is necessary esse through itself, as was shown above.

Eighth: and this is a confirmation of the preceding. That by which those things that agree in the necessity of being differ either is required for the necessity of being, or it is not. If not, then something is accidental. But this is impossible. For it would neither be caused by the essence of that which is necessary being: for then both would have it, since both have the necessity of being. Nor by anything else: for then the esse of each would depend on something else, and thus neither would be necessary being. The consequence is proved: for then, unless that cause existed, that accident would not exist; and consequently their distinction would not exist; and so they would not be two, but one. — If yes, then this is either because it is included in the ratio of the necessity of being, or because the necessity of being is specified through it. Not the first: for then it would be in both, just as the necessity of being is. Not the second: for then it would complete the necessity of being with respect to esse, but not with respect to the intention of the necessity of being, as a difference completes a genus. But this is impossible. First, because for that which is necessary being its quiddity is its esse. Second, because esse would be acquired by it through another: but this is impossible. Therefore etc.

2. It must first be noted that the difference can be compared to the genus in two ways: in one way, according to the absolute quiddity and account of the genus; in another way, in relation to the esse of actual existence. If it is compared in the first way, it is thus not completive of the genus; for the genus, as Saint Thomas says, has its complete account prior to the addition of the dividing difference. — If, however, it is compared in the second way, it is thus completive of the genus. Namely, because it constitutes the proper receptive esse, if it is the ultimate difference: for the most special species does not await another formal principle in order to be, although in material things material principles are required. But if it is not the ultimate difference, it makes the genus draw nearer to esse: because the genus cannot be in act unless it is limited by a difference, as was also shown above ⁸

It must be noted, secondly, that since a genus is limited by its difference and approaches esse, it acquires esse through something other than itself, distinct from it not really but formally: for the difference is not distinguished from its genus really but formally, although in the thing it requires some real distinction and composition. Now this cannot belong to that which is necessary of itself (secundum se), since in it there are no formally distinct elements, as far as the thing considered in itself is concerned. Therefore, when Saint Thomas argues, as an inconvenience, that to necessary being itself esse would be acquired through something else, this is to be understood of another formal otherness subsisting on the side of the thing in itself, which requires some composition in the thing—whether of matter and form, or of essence and esse—of which more will be said below ⁹ the discussion will be fuller.

VIII. Ninth. If there are two gods, then either the name god is said of them equivocally, or univocally. If the first, it does not pertain to the present intention. — If the second, then either the same nature is in both according to one esse, or according to one esse and another. If according to one esse, therefore they will not be two: because those things of which there is not one esse, if they are distinguished substantially. If according to one esse and another, therefore neither will be its own quiddity or its own esse: the opposite of which was shown above.

Concerning that proposition, Two do not have one esse if they are substantially distinct, it must be understood that some things can be understood to be substantially distinguished in two ways: in one way, because they are two substances, one of which is not the other, however they may be substances; in the other way, because they are totally distinct according to essence, so that neither is the essence of the one the essence of the other, nor are both parts of the same essence. The proposition of Saint Thomas, therefore, is to be understood in the second way, not the first. For matter and form of one composite have one esse of actual existence, because they constitute one essence: and yet they are two substances. Socrates and Plato, however, cannot have one esse: because they are diverse essences not constituting one essence in number.

Concerning that conditional, If their nature is, according to one and another esse in themselves, neither will be its quiddity or its esse ¹⁰, it must be noted that a disjunctive consequence is introduced. For if the quiddity of these two is posited as one, while the esse of that quiddity in these two is diversified, it follows that quiddity and esse are really distinguished. And therefore, if one of them is its quiddity, it must be distinguished from the esse; but if it is its esse, it must be distinguished from the quiddity: because, since quiddity and esse are posited as two distinct things, one supposit cannot be identified with both, but, if it is identified with one, it must be distinguished from the other.

IX. Tenth. To that which is necessary being there belongs a necessity of being insofar as it has this determinate and particular esse. Therefore the necessity of being cannot belong to several. Therefore there cannot be several gods. — The first consequence is proved: because nothing that belongs to this determinate thing insofar as it is this determinate thing can possibly belong to another. — The antecedent is also proved. If that which is necessary being is not this determinate thing insofar as it is necessary being, then the determination of its esse is not necessary of itself but depends on another. But each thing, insofar as it is in act, is distinct from all others, which is to have this determinate esse. Therefore necessary being depends on another with respect to esse in act. But this is contrary to the notion of necessary being. Therefore, etc.

2. But it seems that St. Thomas does not prove the proposed conclusion. For the antecedent is: To that which is necessary to be, there belongs the necessity of being insofar as it has this determinate esse. Yet he proves this one: That which is necessary to be is this determinate thing insofar as it is necessary to be. — Likewise, when he ought to subsume, But each thing insofar as it is this determinate thing is in act, he subsumes the converse, namely this: But each thing insofar as it is in act is distinct. Therefore etc.

It is answered that ly does not here specify the formal account, but denotes the foundation and the concomitance. Just as, if I were to say, Socrates inasmuch as this man is in act, the sense is that this man is the foundation of being in act, and that being in act accompanies this man, that is, this designated man, and not man in common. And therefore it makes no difference to this sense to say, Socrates inasmuch as he is this man is in act, and to say, Socrates inasmuch as he is in act is this man. Similarly, then, since in that which must be, the necessity of esse and this designated esse accompany one another—because it does not have the necessity of esse without this designated esse—it makes no difference to say, It has the necessity of esse inasmuch as it is this designated thing, and, It is this designated thing inasmuch as it has the necessity of esse: for this designated esse is the foundation according to which the necessity of esse befits it. The same is said of those propositions, Each thing according as it is this something and distinct is in act, and Each thing according as it is in act is distinct and this designated thing: for in both the fundamental account and the concomitance are denoted. Therefore this proposition, That which must be is not this designated thing inasmuch as it must be, is equivalent to this one, That which must be does not have the necessity of esse inasmuch as it is this designated thing. And likewise the affirmative equivalent of the affirmative holds as regards truth.

The reason is this. If the necessity of being does not belong to that which must be insofar as it is this determinate thing, then its self-designation and particularity are not necessary of itself, but accrue to it from another: for then the necessity of being would not, of itself, accompany that designation and determination of the nature. But this is impossible: since esse in actu accompanies designation and distinction from others, if designation belongs to it from another, then also its esse in actu will be from another.

Nor does it avail if one says, as Aureol does, I Sent. ¹¹, that the philosophers would say that the necessary esse itself would be of another species; and thus, even granting that the singularity of one does not belong to the other, this does not rule out their being several necessary esse's. — That this does not avail is evident. For since they agree in the intention of the necessity of esse, they would then have to be distinguished by something superadded to that intention. But it was shown above, in the eighth argument, that they cannot be distinguished by such an addition.

X. Eleventh. The nature signified by this name god is individuated of itself in this God; otherwise there would be composition in Him. Therefore it is impossible for it to belong to another, because what is the principle of individuation cannot be common to many.

Twelfth. The divine nature cannot be divided, neither by an essential difference nor by an accidental one, as was shown above; nor by division of matter, because it is not in matter. Therefore there are not several gods. — The consequence is evident. For if there were several, they would have to be distinguished in this one and in that one.

Thirteenth ¹². God is abstract esse. Therefore there is only one: because abstract esse is only one. Just as, if whiteness were separate, it would be only one, since of itself it has no multiplicity except from the recipient; just as neither is its ratio multiple, but one.

XI. Fourteenth. The proper esse of any given thing is only one. But God is His own esse. Therefore there is only one God.

But this argument does not seem to conclude. For, given that Socrates were his own esse, it would not follow that there is no man other than Socrates, but only that there is no other Socrates. Thus in the case at hand it does not follow that there is no other God, but that there is no other this God.

It is answered, according to the teaching of Saint Thomas Ver., q. II, a. 1 ¹³, that where the essence of something is its own proper esse, it is impossible for the same to belong to another under the same aspect: just as it is impossible for the proper esse of one thing to be in another thing. And therefore, if humanity in Socrates were identical with Socrates' own proper esse, not only would there be no other Socrates in reality, but neither any other man of the same aspect as Socrates. Similarly, therefore, if the divinity of this God is one with his own proper esse, there can be no other god of the same aspect as he.

2. But the doubt does not seem to be removed by this. For, although the esse of Socrates would be identical with his humanity, it does not follow that humanity of the same rational character is not in another, but only that this humanity is not in another: just as, although the rational in man is identical with animal, and the rational is proper to man, it does not follow that animality according to the same generic rational character is not in others, but only that animality insofar as it is contracted to man is not in other animals.

3. For the clarification of this point, it must be considered that esse, as we said above ¹⁴, does not signify some single nature abstractable from inferiors and contractible through differences; rather, it signifies the most distinct act and the actuality of all things that are in a thing. So that by the same esse of Socrates, Socrates, man, animal, and substance are in the nature of things; nor does it differ in reality, in Socrates, to be Socrates and to be man and to be animal, if these are said to signify actual existence. Similarly in God, it does not differ to be God and to be this God.

From this it follows that, if Socrates is his own esse of actual existence, then just as Socrates is essentially a man, so too he is essentially the esse of a man; and thus the ratio of man in Socrates is the ratio of his actual existence; and therefore, just as his esse is proper to him, so too the ratio of man, predicated of him essentially, is proper to him; and consequently, since the proper esse of Socrates belongs to no other, neither will the very ratio of man predicated of Socrates belong to any other; and, if something else is called a man, this will be according to another ratio. Much more, then, is this found in God, in whom the nature is individual not through anything added, but through itself. For, if God here is his own proper esse, and in him God and being God do not differ, the ratio of God and the ratio of his own esse will be the same. Therefore, if his esse is one alone and belongs to no other, neither will the ratio of God be able to belong to another. And thus there cannot be several gods according to the same ratio, that is, univocally.

To the argument, therefore, it is said first that rather it would follow not only that this humanity of Socrates, but also that humanity would not be of the same account in Socrates and in other men. For the esse of Socrates is not only the esse of this humanity, but is also the esse of humanity simply. And therefore, if esse is not communicated, neither will humanity, which is one and the same with that esse, be communicated.

By way of an objection, it is said that the case is not like the one brought forward concerning the difference. For the difference has the character of an act that contracts and limits, even though it is materially identified with the genus itself. But the character of what is contracted is one thing, and that of what contracts another. Hence it is not unfitting that the character of the difference should belong to only one species, while the character of the genus belongs to many. Esse, however, does not have the character of an act contracting with respect to inferiors, but of the simple actuality of a thing, penetrating whatever it may be inwardly. Therefore, if the thing itself and its quiddity are esse itself, then a single character of quiddity cannot be abstracted from esse itself so that it would be common while esse would be proper; rather there will be one character for both, and if esse is not communicated, neither can the quiddity itself be communicated.

XII. Fifteenth. The divine nature has esse in the highest degree. Therefore it is maximally one. And thus it is not divided into many. — The consequence is proved. Because a thing has esse according to the mode by which it possesses unity. Hence each thing resists its own division as far as it can, lest by this it tend toward non-being.

Note that, since unity follows upon being as its proper passion, adding to it only indivision, the more perfectly a thing is a being, the more it must be one in a more perfect manner. And therefore, if something were being in the highest degree, it must be one in the highest degree and undivided in the highest degree.

But a doubt arises. For ten men are a more perfect being than one man. And yet they are not more one. Therefore the mode of unity is not according to the mode of being. It is answered that ten men are not a more perfect being than one man, but a more multiplied one. And therefore they are not more one, but have several unities.

XIII. Sixteenth. Whatever things are found to agree in some genus must all depend on some one thing: for we see that in every genus there is found one thing which is the measure of the others, and thus multitude proceeds from unity. But all things agree in esse. Therefore there must be one thing which is the principle of all beings.

Seventeenth. In any principality, the one who presides desires unity. For this reason monarchy, or kingship, is the best form of principality. Likewise, among many members there is one head. And thus from this sign it is evident that unity is owed to the one to whom principality is owed. Therefore unity must also be attributed to God, to whom the principality of all things belongs as the cause of all things.

Note that a community is always better governed by one, if he be wise and good, than by many, as is clear from Aristotle in the Politics ¹⁵ and Metaphysics XII ¹⁶. Therefore, since a wise ruler desires to govern his subjects as well as he can, he wishes to be alone in his rule, lest others be in some respect an impediment to him: for the variety of opinions among several rulers often begets confusion, and is no small detriment to the commonwealth. Hence Saint Thomas rightly says that in any principality the one who presides desires unity.

The conclusion is finally confirmed by the authority of Deut. 6, "Hear, O Israel," etc. Likewise Exod. 20, "You shall not have," etc. Likewise Eph. 4, "One Lord," etc.

XIV. From this conclusion a threefold error is excluded. The first was that of the pagans, who posited a multitude of gods, ascribing the name of divinity to all eternal substances, and especially by reason of wisdom, felicity, and governance: although many of the pagans posited one supreme God as the father of all the other gods, such as Borgona or some other.

Saint Thomas adds, moreover, that this manner of speaking—namely, that certain persons are called gods by reason of wisdom, happiness, and governance—is found in Sacred Scripture: as is clear in the Psalm, where it is said, "There is none like you among the gods"; and elsewhere, "I have said, You are gods," etc.

Note that Saint Thomas does not intend by this assertion to say that the immaterial substances themselves are gods properly speaking; rather, his mind is that Scripture sometimes agrees with the gentiles as to the name, but whereas they called those substances gods properly speaking, Scripture names them gods only participatively.

The second error was that of the Manichaeans, who posited two first principles, neither of which is the cause of the other: namely, the principle of all evils and the principle of all goods.

The third error was that of the Arians, who held the Father and the Son to be two gods.

Note that Arius, as is related below in the fourth book ¹⁷, did not hold the Son of God to be true God, but only to be so by a certain participation in likeness above the other creatures. Yet although he did not expressly posit two true Gods, it followed nevertheless from his position—once the truth of Scripture is added—that he was obliged to say that the Father and the Son are two true Gods. For, since it is held from Sacred Scripture that the Son of God is true God, if Arius's position is added to this truth—namely, that the Son is distinguished from the Father according to essence—it follows that there are truly two Gods. And on account of this Saint Thomas added: and yet they are compelled by the authorities of Scripture to believe that the Son is true God.