PART THREE
Thomas had been absent from Italy for some fourteen years when he returned in 1259, more likely than not first going to his home priory in Naples. I say more likely than not because historians are far from being of one mind on how Thomas spent the ten years before his return to Paris in 1269. If he did indeed return to Naples, he would have remained there until 1261 when he assumed the post of lecturer in the convent at Orvieto. It is thought that Thomas was associated with the papal court, which in those years was something of a movable feast, spending time in one town or another north of Rome. In Viterbo there is a pulpit on a street corner from which Thomas Aquinas allegedly preached during these years. From 1265 to 1268, Thomas was regent master at Santa Sabina in Rome.
But of course it is the works Thomas wrote during this period that most interest us. Before leaving Paris he conceived the idea of the Summa contra Gentiles, a work in four books, the first three of which were to be a defence of the faith on the basis of principles available to all, not only to adherents of other religions of the Book, but to non-believers as well. Only in Book 4 does Thomas claim to be mounting formally theological arguments, that is, arguments whose premisses are supernatural truths that God has chosen to reveal. The work was completed in 1265 and we have the bulk of the text in Thomas’s own hand. But the text also indicates another factor in the literary production of Thomas, the help of secretaries. Increasingly, he would dictate to a Dominican sociusassigned to him for this purpose. Reginald of Piperno thus makes his dé but in the career of Thomas, a faithful and devoted companion to the end. But there are other hands in evidence as well, indicating that Thomas had the help of more than one confrère in his writing.
Among the scriptural commentaries contemporary with the Summa contra Gentiles, mention must be made of that on Job. In the prologue Thomas tells us that he intends to produce a commentary on the literal meaning of the text, its moral meaning having been exhaustively treated by St Gregory the Great. Boleslaw Sobocinski, the logician, professed to be an admirer of this commentary because of its logical sophistication. Increasingly, students of Thomas’s biblical writings are recognizing the importance of his commentary on Job. Thomas also composed the extraordinary Golden Chain during this period, beginning it at Orvieto and completing it in Rome. Patristic sources are mined to produce a commentary on the four Gospels: it is one of the most self-effacing of Thomas’s works. He is nowhere in it, yet of course presides over the selection and orchestration of the texts. This is a work that found its way into English because of the interest of John Henry Newman and his fellows in the Oxford Movement.
Thomas’s three-year stay at Santa Sabina is notable for several reasons. First, the Disputed Question on the Power of God, from which we have selected the imposing Question 7 dealing with the divine simplicity and the reach of human language to speak of God. Second, in his final year in Rome, Thomas commented on Aristotle’s On the Soul . This was the first of twelve commentaries on Aristotelian works he would compose during the next five years. Finally, it was in Rome that Thomas began the Summa theologiae, writing there the first part of that magisterial work.
As often as not, Thomas’s teaching on proofs of God’s existence is conveyed by a text in the Summa theologiae in which he gives in crisp and succinct form five proofs, the famous quinque viae. This text has led many to assume that concentration on it alone suffices to understand and appraise the proof. Furthermore, those five ways of proving God’s existence are preceded by a swift dismissal of the argument of St Anselm in his Prologion. The following selection contains both a more extended treatment of Anselm and a number of extremely sophisticated arguments drawn from Aristotle. Since Kant the kind of argument Anselm offered has been called an ‘ontological argument’, and the kind of proof that Thomas favours is called a ‘cosmological argument’: Thomas, in short, is no more impressed by Anselm’s argument here than he would be in the later Summa theologiae, but he asks why it appeals so and has some interesting things to say in that regard. The two lengthy proofs from motion that Thomas lays out are, as he makes repeatedly clear, drawn from Aristotle. This is important because, complicated as these expositions are, they are at key points dependent on arguments that are mentioned but not formulated. The reader thus comes away with a dual conviction. Thomas, as a Christian believer, is insistent that God can be known to exist on the basis of natural reason. But it is also clear that he does not consider such proofs easy of attainment. His respect for Aristotle is palpable as he retains the proof of the Physics. From the perspective of the faith, the truths about God that the Philosopher achieves must look thin and meagre. None the less they attest to the reach of the human mind. The human mind fashions its concepts and forms propositions about the things of which we have sense experience. That our knowledge can extend beyond the sensible is far from being evident. The believer may be so accustomed to talk about God and of the way he exceeds and differs from the things around us that he is tempted to think that God is as available to us as the truth that there are things moving and being moved. That familiarity is the source of the appeal of the ontological argument, Thomas feels. It is not only in following the philosophical effort that Thomas sees how difficult it is. There are reasons within his faith to expect that this will be so. But there are also reasons to expect that it is possible to come to some knowledge of God from the things he has made, from his effects. The following texts represent the best Thomas ever wrote on the subject.
SUMMA CONTRA GENTILES, BOOK 1,
CHAPTERS 9 –14
9. On the manner and order of proceeding in this work.
From the foregoing it is evident that the wise man turns his intention to two kinds of truth in divine matters as well as to the destruction of the errors opposed to them. The one kind of truth pertains to the investigation of reason, whereas the other wholly exceeds the reach of reason. The twofold truth in divine things of which I speak is not on the side of God, who is one simple truth, but on the side of our knowledge, which is diversely related to divine things.
We ought therefore to proceed to showing the first kind of truth with demonstrative arguments by which the adversary can be convinced, but since such arguments cannot be had in the case of the second kind of truth, our intention ought not to be that the adversary should be convinced by such arguments, but rather that the arguments he has against the truth should be refuted, since natural reason cannot be contrary to the truth of faith, as has been shown. A singular way of convincing one’s adversary of such truth is from the authority of Scripture divinely confirmed by miracles, for we can only believe what is above human reason if God reveals it. There are, however, some likely reasons that can be advanced for manifesting such truth for the exercise and solace of the faithful but not for convincing adversaries, because the insufficiency of such arguments would rather confirm them in error, since they might think that it is on the basis of such weak arguments that we assent to the truth of faith.
Proceeding in the manner proposed, we shall first try to manifest the truth that faith professes and reason investigates, setting forth demonstrative and probable arguments, some of which we have gathered from the books of philosophers and saints, so that the truth may be confirmed and the adversary convinced. Then, proceeding from the more to the less obvious, we shall go on to the manifestation of that truth which exceeds reason, answering the arguments of adversaries by probable arguments and authorities, as God provides them, declaring the truth of faith.
Turning, then, to the truths about God that reason can investigate, we shall consider first what belongs to God himself, second, his causing of creatures and, third, the way in which creatures are ordered to him as to their end.
With respect to what belongs to God in himself, let us first lay the necessary foundation for the whole enterprise by considering how God can be shown to exist, for unless this is established, there is nothing else to consider.
10. On the opinion of those who say that the existence of God cannot be demonstrated because it is self-evident.
The attempt to prove that God exists would perhaps seem superfluous to some, namely those who assert that it is self-evident that God exists, so much so that the contrary cannot be thought. In this case it cannot be demonstrated that God exists. Their position seems to follow from these considerations.
Those things are said to be self-evident which are known as soon as their terms are understood. For example, when it is known what a whole is and what a part is, it is immediately known that every whole is greater than its part. But to say that God exists is like that. For by the term ‘God’ we understand something than which nothing greater can be thought. This is formed in the mind of one who hears and understands the term ‘God’, and thus that God exists must be at least in his mind. But it cannot be in his mind alone, since what is in the mind and in reality is greater than that which is in the mind alone. But that nothing is greater than God is shown by the word itself. It follows then that God exists is self-evident, manifest from the very meaning of the term.
Again, it can be thought that there is something that cannot be thought not to exist. And this is manifestly greater than that which can be thought not to be. Thus, something could be thought to be greater than God, if he could be thought not to be, which is against the very meaning of the term. It follows that it is self-evident that God exists.
Again, those propositions are most known in which a thing is predicated of itself, such as, ‘Man is man,’ or of which the predicate enters into the definition of the subject, such as, ‘Man is animal.’ But in God, in a way beyond all other things, as will be shown below, his existence is his essence. It is as if the same answer were given to the questions ‘What is he?’ and ‘Is he?’ Therefore when it is said that God exists, either the predicate is the same as the subject or it is included in the definition of the subject. And thus to say that God exists is self-evident.
Moreover, things known naturally are known in themselves, for they are not known by an inquiry of reason. But that God exists is naturally known, since man’s desire naturally tends to God as to his ultimate end, as will be shown below. Therefore it is self-evident that God exists.
Again, that by which all other things are known must be known of itself. But so it is with God, for just as the light of the sun is the principle of every visual perfection, so the divine light is the principle of all intelligible knowledge, since in him especially is to be found the first intelligible light. Therefore that God exists must be self-evident.
From this and similar considerations some thought that God’s existence is so knowable of itself that its contrary cannot be thought.
11. The disproof of the foregoing opinion and the refutation of the arguments presented.
The foregoing opinion prospers. Partly because from the outset we are accustomed to hear God invoked and hear his name. Custom, especially that which dates from childhood, takes on the force of nature and as a result the things with which the mind has been imbued from childhood take such firm root that it is as if they were naturally known of themselves. Partly because what is self-evident as such and what is self-evident for us are not distinguished. Simply speaking, that God exists is self-evident since what God is is his existence. But because our mind cannot conceive what God is, he remains unknown to us. Similarly, it is simply self-evident that every whole is greater than its part, yet one who has not mentally grasped the notion of whole would not know it. Thus it happens that, with respect to things that are most knowable, our mind is as the eye of a nightbird towards the light of the sun, as is said in Metaphysics 2.
It is not necessary that God be known to exist immediately upon knowing that the name God means that than which nothing greater can be thought, since many of the ancients held that this world is God. Nor from the meanings of the name God that Damascene gives does anything of this kind follow. Even if everyone granted that the name God means that than which nothing greater can be thought, it is not necessary that that than which nothing greater can be thought should exist in reality. The thing and the meaning of the name must be given in the same way. From the fact that the mind conceives what is meant by the name God, it follows only that God is in the intellect. It is not necessary that that than which nothing greater can be thought exist anywhere but in the intellect; it does not follow that in reality there exists that than which nothing greater can be thought. There is nothing absurd in denying that God exists. Nor is it absurd to hold that there can be something greater than whatever be given, in thought or reality, unless one already concedes that that than which nothing greater can be thought exists in reality.
Nor is it necessary, as the second argument proposes, that something greater than God can be thought if he can be thought not to exist. For he can be thought not to exist, not from any imperfection or uncertainty of his existence, since his existence is in itself most manifest, but because of the weakness of our intellect, which cannot intuit him in himself but can know him only from his effects and thus is led to knowledge of his existence by reasoning.
Thus the third argument too is refuted, for just as it is self-evident to us that the whole is greater than its part, so to those seeing the divine essence it is of itself most known that God exists because his essence is his existence. But because we cannot see his essence, we come to know of his existence from his effects and not in itself.
And the response to the fourth argument is also evident. For a man naturally knows God in the way he naturally desires him, but he naturally desires God insofar as he naturally desires happiness, which is a kind of likeness of the divine goodness. For this, it is not necessary that God himself be naturally known to men, but a likeness of him. For it is from his likeness, discovered in his effects, that we come to knowledge of God through reasoning.
The response to the fifth argument is also easily seen. For God is indeed that by which all things are known, not that other things are known only if he is known, as happens in the case of self-evident principles, but because all knowledge is caused in us by him.
12. On the opinion of those who say that God’s existence cannot be demonstrated but can be held by faith alone.
There is another opinion, the contrary of the previous one, which would make useless the effort of those trying to prove that God exists. For they say that reason cannot discover that God exists, but this is accepted only by way of faith and revelation.
Some are prompted to say this because of the weakness of the arguments that others have proposed to prove that God exists.
This position can find false support in the sayings of some philosophers who show that in God essence and existence are identical, namely that what responds to the question ‘What is it?’ and to the question ‘Is it?’ are the same. But we cannot by way of reason come to know of God what he is. Therefore, we cannot by reason determine that he is.
Again, if according to the art of the philosopher one must take as a principle for showing that a thing is what the name signifies, and the notion signified by the name is a definition, according to the Philosopher in Metaphysics 4, there will be no way remaining to demonstrate that God exists, once knowledge of the divine essence or quiddity is removed.
Again, if the principles of demonstration have their origin in knowledge by sense, as is shown in the Posterior Analytics, what wholly exceeds every sense and sensible thing seems to be indemonstrable. But the existence of God is such. Therefore it is indemonstrable.
The falsity of this opinion is shown to us both by the art of demonstration which teaches that causes can be deduced from effects and from the order of the sciences themselves. For if there were no substance knowable beyond sensible substance, there would be no science beyond natural science, as is said in Metaphysics 4. Its falsity is also shown by the effort of philosophers who have tried to prove that God exists. Not to mention Romans 1.20, asserting with apostolic truth, ‘His invisible attributes are clearly seen – his everlasting power also and divinity – being understood through the things that are made.’
Nor ought we to be moved by the fact that in God essence and existence are the same, as the first argument proposed. For this is understood of the existence whereby God subsists in himself, which is unknown to us as to how it is, as is his essence. But it is not understood of the existence that signifies the composition of intellect, for thus God’s existence falls to demonstration when from demonstrative arguments our mind is led to form of God the proposition which expresses that God exists.
In arguments proving God’s existence the divine essence or quiddity is not taken as a middle term, as the second argument proposed, but in place of quiddity the effect is used as middle, as happens in demonstrations of fact. From such an effect the meaning of the name God is drawn. For all the divine names are imposed either by the separation of God from his effects or by some relation of God to his effects.
From this it is clear as well that although God exceeds all sensibles and senses his effects, from which the demonstration is taken for proving that God exists, are sensible. And thus the origin of our knowledge in sense holds even when what is known exceeds sense.
13. Arguments proving that God exists.
Having shown that it is not idle to try to prove that God exists, we go on now to set down the arguments by which both philosophers and Catholic doctors have proved that God exists.
First we will lay out the arguments by which Aristotle proves that God exists. He intends to prove this from the part of motion, and in two ways.
The first of which is this: Whatever is moved is moved by another. It is evident to sense that something is moved, for example, the sun. Therefore it is moved by some other mover. And either that mover is moved or not. If it is not moved, the thesis is proved that it is necessary to hold that there is something moving that is immobile. And this we call God. But if it is moved, it is then moved by some other mover. Either this goes on to infinity or we come to some immobile mover. But it cannot go on to infinity. Therefore we must hold that there is some immobile mover.
In this proof there are two propositions that must be proved, namely, that whatever is moved is moved by another and that in movers and moved things there cannot be an infinite regress.
The Philosopher proves the first of these in three ways. First, thus. If something moves itself, there must be within it a principle of its own motion, since otherwise it is manifestly moved by another. It is also necessary that it primarily be moved, namely that it be moved by reason of itself and not by reason of its part, as when an animal is moved by the motion of its foot, for then the whole would not be moved by itself but by its part, and one part by another. But it must also be divisible and have parts, since whatever is moved is divisible, as was proved in Physics 6. These things being supposed, he argues thus. What is held to be moved by itself is moved primarily. Thus when one part of it rests, it follows that the whole rests. For if when one part rests, another part of it should be moved, then the whole itself would not be what is primarily moved, but the part of it which is moved when the other rests. But nothing that rests when another rests is moved by itself, for that whose rest follows on the rest of another must be such that its motion follows on the motion of that other, and thus it is not moved by itself. Therefore that which was held to be moved by itself would not be moved by itself. Therefore it is necessary that whatever is moved is moved by another.
This argument is not impeded because someone might say that the part of that which is held to move itself cannot rest, and further that the rest or being moved of the part is only per accidens, as Avicenna craftily put it. The force of the arguments consists in this that if something moves itself primarily and as such and not by reason of the parts, it must be that its being moved does not depend on something. The being moved of this divisible, like its existence, depends on parts; and thus it cannot move itself primarily and per se . Therefore it is not required for the truth of the conclusion inferred that it be supposed that the part of the thing moving itself rest as if it were some absolute truth. But this conditional must be true: if the part should come to rest, the whole would come to rest. Which can of course be true even if the antecedent is impossible, just as this conditional is true: if man is an ass, he is irrational.
Second, he proves it by induction, thus: Whatever is moved incidentally is not moved by itself, for it is moved by the motion of another. Similarly neither is that which is moved by violence, as is obvious. Nor is that which is moved by nature, as moved of itself, like animals, which of course are moved by soul, nor what are moved by nature as the heavy and light, because they are moved by the one generating them and removing an impediment. But whatever is moved is moved either by itself or incidentally. If by itself, either by violence or by nature, and this is either moved from itself [ex se ] like the animal, or is not moved from itself, like the heavy and light. Therefore whatever is moved is moved by another.
The third way he proves it is this. The same thing cannot be simultaneously actual and potential in the same respect. But whatever is moved is as such in potency, since motion is the act of something existing in potency just as such. But whatever moves is actual, as such, since nothing acts except insofar as it is actual. Therefore nothing is mover and moved with respect to the same motion. And thus nothing moves itself.
It should be known that Plato who held that every moving thing is moved understood the term motion more broadly than Aristotle. For Aristotle understood motion properly insofar as it is the act of something existing in potency just as such, and as such it is only in divisibles and bodies, as is proved in Physics 6. But according to Plato the thing moving itself is not a body, for he took motion to be any activity, such that to understand and think is a kind of being moved, a mode of speaking that Aristotle himself touches on in On the Soul 3. In this sense Plato said that the prime mover moves himself insofar as he understands himself and wills and loves himself. In some respects this is not in conflict with the arguments of Aristotle, for there is no difference between arriving at some first thing that moves itself, with Plato, and to come to a first that is in every way immobile, with Aristotle.
The other proposition, namely that in movers and moved things there is no infinite regress, he proves in three ways.
The first is this. If in movers and moved things we should proceed to infinity, it would be necessary that all such bodies be infinite, because whatever is moved is divisible body, as is proved in Physics 6. But every body that moves a moved thing is moved at the same time that it moves. Therefore all of these infinite bodies are moved at the same time that one of them is moved. But one of them, since it is finite, is moved in a finite time. Therefore all these infinite bodies are moved in a finite time. But this is impossible. Therefore it is impossible to proceed to infinity with movers and moved things.
That it is impossible for these infinites to be moved in a finite time he proves thus. Mover and moved must exist simultaneously, as he proves by induction in each of the species of motion. But bodies can exist together only by continuity and contiguity. Therefore since all the aforementioned movers and moved things are bodies, as has been proved, it is necessary that they are, as it were, one movable thing by continuity or contiguity. And thus one infinite thing would be moved in a finite time, which is impossible, as is proved in Physics 6.
The second argument is this. In ordered movers and moved things, one of which namely is moved by another in order, it must be the case that if you take away the first mover or if it ceases to move, none of the other things will move or be moved, because the first is the cause of moving in all the others. But if there were ordered movers and moved things to infinity, there would not be a first mover, but all would be as intermediate movers. Therefore none of them could be moved. And then nothing in the world would be moved.
The third proof comes to the same though by a changing of the order, beginning with the higher. That which moves instrumentally cannot move unless there be something that principally moves. But if there is an infinite regress in movers and moved things, all will be like instrumental movers, because they would be posited as moved movers, and nothing would be as the principal mover. Therefore nothing will be moved.
So go the proofs of both the propositions which are supposed in the first way of demonstration whereby Aristotle proves that there is a first unmoved mover.
The second way is this. If every mover is moved, his proposition is true either as such or only incidentally. If incidentally, then it is not necessary, for that which is incidentally true is not necessary. Therefore it is contingent that no mover is moved. But if the mover is not moved, it will not move, as the adversary says; therefore it is contingent that nothing is moved, for, if nothing moves, nothing is moved. But Aristotle takes this to be impossible, namely that at some time there should be no motion. Therefore the first is not contingent, because from a false contingent a false impossible does not follow. Thus this proposition, whatever moves is moved by another, is not incidentally true.
Again, if two things are incidentally linked in a third, and one of them is found without the other, it is probable that the latter can be found without the former. For example if white and musical are found in Socrates, and in Plato musical without white is found, it is probable that in someone else white can be found without musical. Therefore if moving and moved are linked in something incidentally, and being moved is found in something without this that it moves, it is probable that a mover can be found that is not moved. Nor can the instance of two, one of which depends on the other, be advanced against this, because they are linked per se, not incidentally.
But if the foregoing proposition is true per se, a similar impossibility or absurdity follows – because either it must be that the mover is moved by the same species of motion whereby it moves, or by another. If the same, then it will have to be that what alters is altered, and further that what heals is healed and that the teacher is taught and with respect to the same knowledge. But this is impossible, for it is necessary that the one teaching have knowledge and the learner not have it, and thus the same thing would be had and not had, which is impossible. But if it is moved by some other species of motion, such that the altering is moved locally, and the local mover is increased in size, and so on with the others, since the genera and species of motion are finite, this cannot go on to infinity. Thus there would be some first mover that is not moved by another. Unless perhaps someone should say that a turnaround takes place in such a way that, having completed all the genera and species of motion, we must go back to the first, and that which moves according to place is altered and the altering is increased, and that which causes increase would be moved according to place. But from this would follow the same as before, namely that that which moves according to some species of motion is moved according to the same species, although mediately, not immediately.
We are left then with the necessity of holding that there is some first which is not moved by another outside it.
But because, given that there is a first mover that is not moved by anything external to it, it does not follow that it is in every way immobile, Aristotle continues, saying that this can be in either of two ways. First, such that the first is in every way immobile and, given that, the position is secured, namely that there is some first immobile mover. In another way, such that the first is moved by itself. This seems probable, because what is of itself is always prior to that which is because of another. So it is reasonable that in moved things the first is moved by itself and not by another.
But, given this, the same thing follows again, for it cannot be said that the whole is moved by the whole in the thing moving itself, because then the aforementioned absurdities would follow, namely that someone would at the same time teach and be taught, and similarly in the other motions, and again that something would be simultaneously in potency and in act, for the mover as such is in act, and what is moved is in potency. So it remains that one part of it alone is moved and the other moving. And thus the same thing as before follows, namely that something is an unmoved mover. It cannot be said that both parts are moved such that one is moved by the other, nor that one part moves itself as well as the other, nor that the whole moves the part, nor that the part moves the whole, because the previous absurdities would follow, namely that something is at the same time and with respect to the same motion mover and moved, and at the same time in potency and in act, and further that the whole would not be moving itself primarily but by reason of its part. So it follows that in that which moves itself, one part must be immobile and moving the other part.
But because in the things moving themselves that we know of, namely animals, the moving part – that is, the soul – although it is immobile of itself, still it is moved incidentally, he goes on to show that in the prime mover the part moving himself is not moved either as such or incidentally.
The things we know of that move themselves, namely animals, being corruptible, the moving part in them is moved incidentally. But corruptible self-movers must be reduced to some prime self-mover that is sempiternal. Therefore it is necessary that there be some mover of that which moves itself which is not moved, either per se or incidentally.
That it is necessary, on his view, that something moving itself be sempiternal is clear, for if motion is sempiternal, as he supposes, it is necessary that the generation of self-movers that are generable and corruptible should be perpetual. But the cause of this perpetuity cannot be one of the self-movers that is not always. Nor all at the same time. Both because they would be infinite, and because they would not all be at the same time. Therefore it remains that there must be some perpetual self mover that causes the perpetuity of generation in the lower self movers. And thus its mover is not moved either as such or incidentally.
Again, we see in self-movers that some begin to be moved afresh by some motion that is not caused by the animal itself, such as by digested food or a change of air, by which motion the thing moving itself is moved incidentally. From this it can be concluded that nothing moving itself is always moved if its mover is moved per se or incidentally. But the prime self-mover is always moved, otherwise his motion could not be sempiternal, since every other motion is caused by the prime self-mover. It remains then that the prime self-mover is moved by a mover that is not moved either as such or incidentally.
Nor is this argument threatened by the fact that movers of the lower orbs cause a sempiternal motion and yet are said to be moved incidentally, because they are said to be moved incidentally not by reason of themselves but by reason of their mobiles which follow the motion of the higher orb.
But because God is not a part of any self-mover, Aristotle pursues the matter further, in his Metaphysics, proceeding from this mover which is a part of the self-mover to another wholly separate, who is God. For since every self-mover is moved by desire, it is necessary that the mover that is part of a self-mover should be moved on account of some desirable. Which is superior to it in moving, for the desirer is in a certain way a moved mover, but the desirable is a mover wholly unmoved. Therefore it must be said that the separate prime mover is completely immobile and this is God.
Two things seem to weaken these arguments, of which the first is that they proceed on the supposition of the eternity of motion, which Catholics take to be false.
To this it must be said that the most efficacious way to prove that God exists is on the supposition of the eternity of the world since on that assumption it seems to be less obvious that God exists. For if the world and motion began as new, it is plain that there must be some cause which produces the world and motion, because whatever begins as new must take its origin from some cause, since nothing brings itself from potency to act or from not existing to existing.
The second difficulty is that the foregoing arguments presuppose that the first moved, namely the celestial body, is moved from itself, from which it follows that it is animate, and that is not conceded by all.
To this it should be said that if the first thing moved is not held to be moved from itself, it is necessary that it be immediately moved by the wholly immobile. Hence Aristotle introduces this conclusion under a disjunction: namely that we must either come to a separated first unmoved mover, or to something moving itself, from which again we come to a separate first unmoved mover.
The Philosopher proceeds in another way, in Metaphysics 2, to show that there cannot be an infinite regress in efficient causes, but we must come to one first cause, and this we call God. That way is this. In all ordered efficient causes, the first is the cause of the intermediate and the intermediate the cause of the last, whether there be one or many intermediates. The cause being removed, that of which it is the cause is removed. But if in efficient causes there is an infinite regress, none of the causes will be first. Therefore all the others are removed, since they are intermediates. But this is manifestly false. Therefore we must recognize that there is a first efficient cause that is God.
There is another argument that can be fashioned from the texts of Aristotle. For in Metaphysics 2 he shows that those things which are most true are also the greatest beings. But in Metaphysics 4 he shows that there is something most true, from the fact that we see that of two falsehoods one is more false than the other, hence it is necessary that one thing can be truer than another. But this is according to approximation to that which is simply and most true. From which it can be concluded further that there is something which is maximal being and this we call God.
Another argument to the same effect, put forward by Damascene, is drawn from the governance of things, which the Commentator also gestures towards in Physics 2, and it is this. It is impossible that contrary and dissonant things can harmonize in one order always or usually except by someone’s governance, by which each and all are made to tend to a certain end. But in the world we see things of diverse natures harmonize in one order, not rarely and by chance, but always or for the most part. Therefore it is necessary that there be someone by whose providence the world is governed, and him we call God.
14. That the way of negation is necessary for knowledge of God.
Having shown that there is a first being that we call God, we must investigate his characteristics.
The way of remotion [or negation] is chiefly to be used in the consideration of the divine substance since the divine substance exceeds by its immensity every form that our intellect can attain, and thus we cannot apprehend it by knowing what it is. But we have knowledge of a sort of it by knowing what it is not. We come closer to knowledge of it insofar as we are able with our intellect to remove more things from it. We know anything more perfectly when we grasp more fully its differences from others, for each thing has its proper existence distinct from that of all other things. Hence in things whose definitions we know, we first place a thing in a genus, by which we know generally what it is, and afterwards add differences by which it is distinguished from other things, and thus complete knowledge of the substance of the thing is achieved.
But because in considering the divine substance we cannot grasp what it is as a genus nor its distinction from other things by affirmative differences, we must grasp it by negative differences. For just as a positive difference contracts a thing, we approach nearer to the complete designation of the thing insofar as more distinctions are made. So too when we say that God is not an accident, he is thereby distinguished from all accidents, and then if we add that he is not a body, we distinguish him also from some substances, and thus by such negations he is distinguished in an orderly way from everything that is other than himself. His substance will be properly thought of when it is known to be distinct from everything, but this will not be perfect knowledge, because what he is in himself will not be known.
Therefore in discussing God by way of remotion, we take as a principle that which is obvious from the foregoing, namely that God is in every way immobile. The authority of Sacred Scripture confirms this, for it is said in Malachi 3.6, ‘For I am the Lord and I change not’; in James 1.17, ‘With whom there is no change nor shadow of alteration’; and in Numbers 23.19, ‘God is not a man, that he should lie: nor as the son of man, that he should be changed.’