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Aspects of Aquinas

30 November, 1999

Rev Francis Selman offers a fresh insight into many of the features of St Thomas Aquinas’s work with sections on God, the human being and moral life, as well as the means of salvation by Christ, the emotions, the resurrection, and our being drawn to God not only by our intellect but also by our love.

240 pp, Veritas, 2005. To purchase this book online, go to www.veritas.ie .



1. How can we know God?
2. Creation
3. Good and evil
4. Word and image
5. Angels
6. The soul
7. The emotions
8. The virtues
9. The Old Law
10. The sacrament of salvation
11. The Eucharist
12. The resurrection
13. Charity and friendship



In Aspects of Aquinas Rev Francis Selman offers a fresh insight into many of the more salient features of Aquinas’ work with sections on God and how we know ‘Him’, good and evil, human, moral life and Christ as the means of salvation. Aquinas may have placed a premium on intellectual approaches to faith, but he also demonstates how we are drawn to God by love.The author includes chapters on some of the more overlooked aspects of Aquinas’s writings including his work on the emotions and the resurrection. The book includes a glossory offering definitions of key philosophical terms making it very useful for novices and scolars of St Thomas alike.

Chapter One : How can we know God
For St Thomas, God is the beginning and end of everything; everything comes from him and returns to him. Theology for St Thomas is first of all about God and only about other things in view of God, as they come from or go back to him. Thus the first question for St Thomas is about God. Contrary to those who think that belief in God is just a matter of faith, St Thomas thought that we can know that God exists, beginning with our natural knowledge of things. In this way we can come to know that God exists as the cause of things. But he did not think that we can know what God is. As he says in the Summa, ‘because we do not know what he is, but what he is not, we cannot consider how God exists but rather how he does not exist.’ (1) When he says ‘how he does not exist’, he means not as a body, not finite, not changing, as visible things are, but infinite, immutable and eternal. St Thomas makes his own the sentiment of Pseudo-Dionysius: ‘we are joined to God as to the unknown.’ (2)

At present it is common to emphasise the negative aspect of our knowledge of God, which St Thomas shares with the tradition of the Eastern Fathers. But it is possible to exaggerate the negative theology of St Thomas, as though we could not know anything about God. St Thomas himself adds
to the words of Pseudo-Dionysius quoted above, ‘we know him more fully, however, inasmuch as several and more excellent effects of his are shown to us and we attribute some things to him out of divine revelation, which natural reason does not reach, as that God is three and one.’ St Thomas would hardly have said in the prologue to the second question of the Summa that the principal intention of sacrea doctrine is to hand on a knowledge of God (cognitionem dei tradere) if he had thought that God remains completely unknown and inaccessible to us. He even thought that it would be contrary to divine goodness if God did not communicate to us some knowledge of himself. (3) What then did St Thomas think we could know about God?

First it should be said that St Thomas thought we can know about God in two ways: by reason and by grace. The light of reason itself is, St Thomas liked to say, quoting Psalm 4:6, as though ‘the light of your face signed on us.’ Grace is an additional light, which enables us to know things that reason cannot reach by its own strength. This second way of knowing God is itself divided into two: faith in this life and the light of glory we need to strengthen our mind to see God in the next life. St Thomas compares the knowledge that reason and faith give us in the following way: the doctrine of faith is a higher and more certain adherence than natural knowledge, although it is imperfect in explaining what is above the power of reason and our understanding. Faith adheres more certainly inasmuch as divine revelation is more certain than human knowledge. (4)

By the light of reason, St Thomas says, we can know that God exists as the cause of the world, because effects resemble their cause and bear a likeness to their cause. Every piece of music by Mozart, for instance, bears the inimitable stamp of its composer. We have to start with created things in order to come to know about God by natural reason, St Thomas says, because all our knowledge takes its beginning from the senses. Created things can lead us to know that God exists, but they cannot let us know what he is, because they in no way match the cause of all things. (5) It is because created things are in some way like their cause that they allow us to know something about God, but because they fall far short of him that we cannot speak of created things in the same way. Thus we can only speak of God by analogy. We draw an analogy between things when they are alike in some respect but differ in nature. We may talk about the moaning of the wind because it sounds like someone moaning, although the wind is quite different in nature from a human being. The philosopher John Locke tells us that some people fancy the idea of scarlet is like the sound of a trumpet. (6) Although scarlet differs from a trumpet in nature as a colour does from a sound, they may be likened one to the other by an analogy, because the brilliant colour of scarlet may have a similar effect on me as the piercing notes of a trumpet do.

St Thomas drew his doctrine of analogy from the Divine Names of Pseudo-Dionysius. St Thomas’ attention had first been drawn to this work by the lectures of St Albert when they were in Cologne. Pseudo-Dionysius says that, as God is hidden and beyond anything we can describe with words, we should think of God as much as he reveals about himself to us, and not say anything about his hidden divinity except what is expressed in the sacred sayings of Scripture, which he says shed a spiritual light like rays of light in our mind. (7) Pseudo-Dionysius observes that when we praise God as wise and almighty, good and strong in hymns, we apply names to him. We notice, by way of contrast, that St Thomas did not just think we could name God from the sayings revealed in Scripture but also from created things. Applying names to God raises two questions: If we can apply many names to God, is this not contrary to his simplicity? Should there not rather be one name for God? And, secondly, as God is far above creatures, what knowledge of him can any of our words give us? St Thomas makes clear that we do not know God as he is through the divine names, because he is ineffable and unfathomable; but they let us know God as the source and cause of the power, goodness and strength in created things. (8)

In saying that we can speak about God by analogy, St Thomas differed sharply from Moses Maimonides (11351204), who was a contemporary of Averroes in Cordoba until 1165, when persecution by the Moorish ruler in that city made him flee to Cairo, where he ended his days as father of the Jewish community and court physician to the Caliph there. The Guide of the Perplexed was an attempt to reconcile Jewish faith with reason rather as St Thomas later did for the Christian faith in the Summa contra Gentiles. Maimonides thought that God cannot be simple if he possesses attributes. Thus he denied that we can say anything affirmative about God, in order to uphold his simplicity. All positive names for God, Maimonides declared, are equivocal: that is, we mean quite different things by them for God and for creatures, so that they do not really tell us anything about God. For instance, he thought that we use the word ‘exist’ in altogether different ways about God and creatures. Maimonides did not think that there could be any analogy between creatures and God, because he did not think that they have a relation to Him. He also thought that to ascribe attributes to God implies that he has qualities. (9) In Maimonides’ view, we can only speak about God negatively and the names of God are to be understood in a negative way, so that when we call God wise we mean he is not ignorant. Only negations lead us to a knowledge of God, he says; only negative attributes are permitted or, if there are any positive ones, they apply to the actions of God. (10) St Thomas, however, thought that we are not confined to negative names but can speak about God affirmatively because, as he points out elsewhere, every negation rests on an affirmation.” For example, you cannot say someone is ignorant unless you know what knowing is, or that something is insoluble unless you know what soluble means.

What then allowed St Thomas to think that we can speak about God affirmatively by analogy when Maimonides denies this? We can see that there are two reasons. First, St Thomas drew a crucial distinction between the way a word signifies and what it signifies.” How a word signifies, he says, is as we use it of creatures, that we are familiar with and know more closely, but what it signifies belongs more to God since God is more truly good, or wise, or strong than any creature. Secondly, we can speak of God by analogy because creatures participate in God. We speak by analogy because God does not participate in anything, but creatures do. You cannot share in anything unless it exists before you. For instance, I share in human nature because I received human nature from beings who had it before me. But nothing exists before God, so that he can receive it from anyone or thing before him. This doctrine of participation comes from Plato: we find it well stated in the Phaedo 100c, where he opines that the things we see are beautiful because they share in beauty itself. St Thomas’ source for it was Pseudo-Dionysius. Maimonides, then, did not allow us to speak about God by analogy, because he lacked the doctrine of participation. St Thomas, however, agreed with Maimonides that we cannot apply our names to God and creatures in just the same sense, or univocally, because God does not participate in anything but creatures do. When we say that creatures participate in God, We do not open the way to some kind of pantheism but mean that all the perfections we find in creatures, such as being good, wise or powerful, derive from God as their source. On the other hand, if our names for God are merely equivocal, as Maimonides thought, St Thomas did not see that there is any order or likeness of creatures to God.

We can speak of God by an analogy with creatures, because they have a likeness to God, as all effects are in some way like their cause. Thus we name God after creatures. We take our various names for him, such as good and wise, from the diverse perfections that we find in creatures and attribute them to him as the primary source of those perfections.(13) Nothing that we know would be good or wise unless God were good and wise. He is the source of all perfections, which, as it were, come forth from God in what St Thomas calls ‘the procession of creatures from God.’ We name creatures after God, St Thomas observes, because we can only name things as we know them, and what we know first is created things. (14) What allows us to name Him after them is that He is the source of every perfection in them: ‘God is known through the divine names as their principle and cause.’ (15)

We speak about God by analogy, because the perfections of creatures exist in God in a far higher way as the source of them. The perfections in creatures pre-exist in God and creatures derive them from Him by sharing, or participating, in them. We have to speak of God by analogy because these perfections exist in God and in creatures in a different way. God is not just wise, good and powerful: He is Wisdom, Goodness and Power itself. This is not true of any creature: they may be good or wise but none is Wisdom or Goodness itself. Solon was wise but is not Wisdom; wisdom is rather something that he shared in. When we call God ‘living’, we speak by analogy because creatures are living but God is Life itself. This is because everything that receives something like existence, life or goodness goes back to something that does not receive these perfections from another or, therefore, share in them. God does not share in life: He is Life; all life comes from Him. Thus speaking about God affirmatively by analogy is known as the ’eminent way’, because the perfections in creatures, after which we name God, exist in Him in a higher manner.

When we name God from the diverse perfections in creatures, we do not, however, as Maimonides feared, take away the simplicity of God, since the perfections that are found in many creatures exist simply in God, for they are all one in him. This follows from the point I have just made above: as God is not just wise but is Wisdom, and not just living but is Life, not only is God identical with each of his attributes, but each attribute is identical with the others. If God is His wisdom and is His life, His wisdom is His life and His life is His goodness and so on. Thus the many names of God do not detract from his simplicity, because they all name one thing in reality. As St Thomas says, the various names that we apply to God do not derive from any diversity in God but from the diversity of perfections we find in creatures, which we then attribute to God as their cause. (16) The question then arises, whether our different names for God really have a different meaning or whether we might as well use only one name for God, seeing that all our names mean the same thing in reality. St Thomas’ reply to this question is that, although what our names signify is a single reality, they do so in many respects. They are not just synonyms, because they have diverse meanings in our mind, even though they refer to one thing in reality when applied to God.(17) God has created a great variety of creatures to manifest his perfections, because no one created thing could adequately represent the goodness, power and wisdom of God. As St Thomas says, there is only one adequate representation of the divine nature: it is the divine Word.

The Analogy of Being
We speak of God by analogy because created things are like God in some respect. They are like God, St Thomas remarks, not God like them, just as we say that a portrait is like its subject, not a man like his portrait. The first way in which creatures are like God, he says, is that they exist. We use the verb ‘exist’ for God by analogy, because created things exist but God is also Existence itself. As St Thomas says, God is Being (Ens) but they are only beings (entia) by participation. (I8) This is because they receive, and so share in, existence. The English language allows us to bring out this difference between God and creatures quite clearly. God is simply Being, with a capital ‘B’; we would, or should, not call God a being, with a little ‘b’. Conversely, any created thing is a being but we do not call any created thing being by itself; it is a being. If we call God ‘a being’ this would make him like other things, as though he were just one among other beings. Then we would be using ‘being’ of God and other things univocally, not by analogy. This shows why it is inappropriate to talk, as some contemporary philosophers of religion do, about ‘a universe in which God exists’, as though God were an item among other items in the universe and not greater than the whole universe. God cannot be an item in the universe, as it all comes from Him.

St Thomas saw what philosophy says about God as Being, or Existence, itself as confirmed by scripture in the passage where God reveals his name to Moses as ‘I am He who is’ or, in the Latin version that St Thomas used, quite simply ‘He who exists’ (Qui est). (19) St Thomas thought that this is the most appropriate name that can be given to God, because it does not in any way limit what he is but is the widest of all names. (2O) We may now sum up St Thomas’ doctrine of analogy under the following five points. God is the source of all perfections in creatures. But we apply our names for these perfections to God by analogy, because they exist in him in another and higher way. First they exist in God in an eminent way, because he is not just living but Life itself. And secondly, following from this, the perfections that are multiple in creatures all exist simply in God, as he is identical with each of his attributes. As they are all one in him, who is their source, the names we attribute to God do not take away his simplicity.

The Negative Way
We can say some things of God affirmatively by analogy, as he is the cause of all creatures, and thus of every perfection in them. But we also speak of God negatively, because we do not know what God is. Indeed, the affirmative way leads to the negative way. First we have to speak of God by analogy, St Thomas says, because what we name exists in God in a way that altogether surpasses the meaning of our words. (21) It is just because, when I call God good or wise I do not mean that he is good or wise just like created things, that I also speak of God negatively. For, in affirming that God is good, I may also deny this of him in that he is not good in any way that my words could express. The way in which we also deny whatever we affirm of God is neatly summed up for us by St Thomas as follows:

Just as the names we impose on things can be predicated of God because there is some likeness of created things to God, so too, as created things fall short in representing God, the names we impose can also be removed from God, and their opposites be predicated of him. (22)

The negative way, then, is also known as the way of removal (via remotionis). It is the reverse side of the affirmative way. The two ways are related, because we can impose names on God as creatures have a likeness to him, but we also remove them because creatures fail to represent God adequately. Thus whatever we affirm about God also has to be taken away, because God is good but not good in any way we know or, therefore, can say. St Thomas points out, however, that we do not speak of God negatively because of anything lacking in him but because God far exceeds everything that we can know.

To speak of God negatively is to say what he is not. St Thomas gives three reasons why we cannot know what God is. First, the mind of no created being can see God by its own natural power, because God infinitely surpasses everything in nature. We shall only know what God is when we see the divine essence but, to do this, the mind first needs to be strengthened with the light of glory. Secondly, we shall never know God completely because we can only know something as it exists, but God’s existence is infinite. Thirdly, when we say what a thing is we define it. To define it is to set limits to the way it exists, but there are no limits to God’s existence. We narrow down something when we say that this living thing is an animal rather than a plant, and this animal a kind of cat, and this cat a lion rather than a leopard. As St Thomas points out, the nearer we come to know what something is, the more differences from other things we add. But as we do not know what God is we can only say how he is distinct from other things by negative differences. Thus we cannot know what he is, but we have some knowledge of him by knowing what he is not. (23) For example when we say that God is infinite, immutable, immense, we remove limits from his existence and say that he is not one of finite, measurable or changing things.

The Divine Light
One reason why we do not know what God is, is that the divine light is hidden from us by its simplicity. We may use here an analogy with ordinary light, which also illustrates what we have said above about analogy. Just as we cannot see pure light by itself but only when it is reflected by other things in the various colours of the spectrum, so we do not know God as he is but speak of him from created things, which reflect their Maker. And just as pure light is refracted into the colours of the spectrum when passed through a prism, so God is reflected in the diverse perfections of creatures. As the colours of the spectrum can then be recombined into the original beam of pure light by being passed through a second prism, so the diverse perfections of creatures are one in their source. Thus the many attributes we ascribe to God do not take away his simplicity. As Cardinal Newman aptly says: ‘the pure and indivisible Light is seen only by the blessed inhabitants in heaven; we have such faint reflections of It as its diffraction supplies. (24) As St Thomas says, quoting St Paul, if anyone could see God he could not express it. When relating his visions, St Paul says that he heard words that could not be uttered (arreta rhemata, literally ‘unsayable sayings’). (25) Our knowledge of God in the present life differs from what the saints share in the life to come. We cannot now see the essence of God, but are instructed about him through the veil of words in Scripture and by the likeness of his effects in created things. (26)

St Thomas sums up what he says we can know about God in the present life with these words:

We know God most of all as the unknown, because the mind is found to know God most perfectly when it is known that his essence is above everything it can apprehend in the state of this life; and so, although it remains unknown what he is, it is however known that he exists. (27)

Thus we can know that God exists but not what he is. What we know of God is that he far surpasses anything we can know in this life. What St Thomas says is not that we do not know God but that we cannot comprehend him. (28) Incomprehensible is not the same as unknowable. To comprehend something is to take in all of it, to get your mind right round it. St Thomas says that we comprehend something when we know it perfectly. We cannot even know God like this in all eternity, for he is infinite and so always surpasses what we know, just as when you reach the horizon you find that another horizon lies beyond it. We shall never comprehend God, but even in this life, St Thomas says, we can touch Him (attingere) by faith.

St Thomas would hardly have called faith ‘a light’ unless he thought that it gives us some knowledge of God. ‘The light of faith’, he says, ‘is as though a stamp of the First Truth on the mind’. (29) Faith joins us to what is unknown and unsayable, not as though it is known, for then it would be plain vision, but ‘unspeakably and obscurely’, for now we do not see clearly but ‘as though in a mirror’. We are joined by faith to the ineffable and unknown, that is, to the divine truth, which surpasses all human speech and knowledge, otherwise we would have open vision but we see only as in a mirror. (3O) By faith, however, we are joined to the unknown imperfectly, because we are joined to what is above the power of natural reason. ‘By the light of faith the mind is raised above itself in contemplation, in that it knows God to be above everything it knows from nature. (31) As St Thomas notes, reason inquires but the understanding contemplates. (32)

If God were altogether unknowable we would have to keep silence about him, for we would be quite unable to say anything. But this was not the mind of St Thomas, who wrote a great deal about the question of God. St Thomas, however, thinks that there is a place for silence when we consider God, ‘God is honoured by silence, not because we do not say or ask anything about him but because we understand that we fail to comprehend him. (33)

The saints, he says, revere the unspeakable things of God with a chaste and silent mind. (34)

In this way St Thomas resolves the apparent contradiction of saying that we do not know what God is, yet can speak of Him affirmatively as well as negatively. When we name God and give Him attributes, we mean that He is that and, at the same time, He is not that, because He is so much more than anything we can say with our words. So we can name God, though he remains hidden and unknown. Thus the God we can speak of by analogy remains the hidden God of Isaiah in St Thomas: Truly, you are a God who hides himself. (35) In the end we pass beyond reason, which only enquires, and come to contemplation that simply beholds Him.

1. ST la q.3 prologue.
2. Ibid la 12, 13 ad 1.
3. De Divinis Nominibus c.1 lect.I, paragraph 36 in Marietti edition.
4. Ibid c.1 lect.1 (7-9).
5. Contra Gentiles (CG) I c.3.
6. An Essay Concerning Human Understanding (1690) 1 c.4, 5.
7. Aquinas, De Div. Nom. c.1 lect.1 (11).
8. Ibid c.1 lect.2 (45).
9. The Guide of the Perplexed I c. 54.
10. Ibid 158
11. De Pot. 7,5.
12. ST la 13,3.
13. De Div. Nom. c.llect.2 (53).
14. ST la 13,1.
15. De Div. Nom. c.1 lect.2 (53).
16. Ibid c. 1 lect.2 (54)
17. ST la 13,4.
18. Ibid la 3,4.
19. Ex 3,14.
20. ST la 13,11.
21. Ibid la 13,5.
22. De Diu. Nom. c.1 lect. 1 (30).
23. CG I c 14.
24. A Grammar of Assent (1870 Longman, Green 1947) 100.
25. 2 Cor 12,4.
26. De Diu. Nom. c.1 lect.2 (64).
27. Super Librum Baetii de Trinitate Proem. q.l,2 ad 1. St Thomas wrote
his commentary on the De Trinitate of Boethius in Paris, 125758.
28. ST la 12,1 ad 3.
29. Super Librum Baetii de Trin. lect.1 q.l, 1 ad 4.
30. De Diu. Nom. c.1 lect.1 (8). Cf. 1 Cor 13,12.
31. Super Librum Baetii de Trin. Proem. q.I,2.
32. Ibid q.6, 1.
33. Ibid Proem. q.2,1 ad 6.
34. Ibid c.1 lecU (44).
35. Isa 45,15.

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