A Very Short Introduction to Aquinas


A friend of mine claims that once in a restaurant he overheard one waiter saying to another waiter: "He's eaten it." When you catch a snippet of conversation like that you begin to be puzzled about its context. It's going to be a little like that with what follows. We are going to overhear fragments of talk, and I am going to try to fit them into a context.

Imagine you are passing the open window of a lecture room in the University of Paris one autumn in the thirteenth century. The room is crowded with young men who are going to be teachers or preachers (or both), and their lecturer, a Dominican friar called Thomas Aquinas, is starting his course of lectures by telling them that if they are going to teach or preach they themselves must first of all be taught by God:

God has destined us for a goal beyond the grasp of reason—No eye has seen what you have prepared for those who love you—and since we must set ourselves this goal and pursue it we needed teaching about it beforehand. We even need revealed instruction in things reason can learn about God. If such truths had been left to us to discover, they would have been learnt by few over long periods and mingled with much error; yet our whole well-being is centered on God and depends on knowing them. So, in order that more of us might more safely attain him, we need teaching in which God revealed himself (Summa Theologiae, la, 1, 1).

Aquinas treats theology as a practical matter. He is not interested in spinning theories about angels and the points of a pin. He is concerned with human well-being. Behind what he says is the image of people going somewhere: we have a "goal," and (more mysteriously) a goal "beyond the grasp of reason." Human well-being, he thinks, is a kind of journey, but a journey into the unknown, towards a destination we only dimly perceive by faith. I think here of the medieval folktale of the youngest son going out to seek his fortune. I used to think that he was going out in search of a fortune, a whole lot of money, but of course he wasn't: he went to seek his fortuna, his luck.

For Aquinas the goal is already partly with us in the journey itself. For him the world is good—but not good enough. For him there is no evil in this material creation. Everything that is, is good. Every being has God within it holding it in being. It is just that some goods are greater than others. Evil comes in when we neglect some great good for the sake of some trivial good: when we sacrifice, say, being just and loving for the sake of being rich. Evil, for Aquinas, is a purely spiritual thing. It belongs to the world of minds and policies and decisions—and even there it is not a positive thing but a failure, a failure to want the good enough. The material world, however, is innocent, and more than innocent; it is the scintillating manifestation of the love of God.

All the more important, then, that we get our priorities right, and, to a certain extent, we can get them right if we keep our emotions in order and exercise ordinary good sense. We can try to use maps, but, in the end, ours is a journey without maps because it is a journey beyond the human horizon, a journey towards living with God himself. We are fortunate enough, lucky enough, to be personal friends of God—this good luck is what Thomas calls "grace." So our journey is really more like a treasure-hunt—we are guided only by certain clues. But God, Aquinas is telling his students, is generous even with the clues. He tells us not only things we couldn't know of ourselves. He even tells us some things that we might have found out for ourselves if we were clever enough. And he does this, says Aquinas, because the journey to human well-being is not just for intellectuals, not just for an elite, the well-educated, the perceptive. God has distributed his clues to all of us, showing us how our lives can be more human, showing us how we can become divine, because he loves all of us.


Thomas Aquinas thought that theologians don't know what they are talking about. They try to talk about God, but Aquinas was most insistent that they do not, and cannot know what God is. He was, I suppose, the most agnostic theologian in the Western Christian tradition—not agnostic in the sense of doubting whether God exists, but agnostic in the sense of being quite clear and certain that God is a mystery beyond any understanding we can now have.

He was sure that God is because he thought that there must be an answer to the deepest and most vertiginous question, "Why is there anything instead of nothing at all?" But he was also sure that we do not know what that answer is. To say it is God who made the whole universe, and holds it continually in existence from moment to moment (as singers hold their songs in existence from moment to moment), is not to explain how the universe comes to exist. For we do not know what we mean by "God." We use this word just as a convenient label for something we do not understand. For Aquinas, only God understands what God is. Aquinas thought that in the Bible God has promised us that one day he will give us a share in his self-understanding, but not yet. Until that day, although God has begun to reveal himself in his Word made flesh, we grasp his self-communication not by coming to know, but only by faith. Faith is an illumination that appears as darkness: we come to know that we do not know.

Aquinas thought we know of God only by trying to understand the things he has done and does for us—the marvelous works of his creation, the even more marvelous works of his salvation, God's personal love for creatures who have rejected him by sin—the whole story that he tells us in the Bible. But none of these works are adequate to show us God himself—no more than you could come to understand the mind of Shakespeare or Beethoven by hearing them ask you to pass the salt:

Our natural knowledge starts from sense-perception and reaches only as far as things so perceived can lead us, which is not far enough to see God in himself. For the things we sense, though effects of God, are not effects fully expressing his power. But because they do depend on him as their cause, they can lead us to know that he exists, and reveal to us whatever is true of him as first cause of all such things, surpassingly different from all of them . . . God's gracious revelation . . . strengthens our natural light of intelligence . . . Although in this life revelation cannot show us what God is in himself, but joins us to him as unknown, nevertheless it helps us to know him better, showing us more and greater works of his (ST la, 12, 12 and 12, 13).

For Thomas Aquinas, our proper and reasonable response to God is not one of exact analysis but of prayer. People who think they have no belief quite often say that they want to pray but do not know who or what they could be praying to. Aquinas would not say to such people, "Ah, but you see, if you became a believer, a Christian, we would change all that. You would come to understand to whom you are praying." Not at all. He would say to such people, "If you became a Christian you would stop being surprised by or ashamed of your condition. You would be happy with it. For faith would assure you that you could not know what God is until he reveals himself to us openly." Praying without knowing, or expecting to know, to whom you are praying is the normal and natural way for a Christian. For now what matters is not knowledge; what matters is faith and confidence in the love of God for us, and the courage to share in that love and pass it on to others—until the time when God's promise is fulfilled. "For now we see in a mirror, dimly, but then we will see face to face. Now I know only in part; then I will know fully, even as I have been fully known" (1 Cor 13:12).


According to Thomas Aquinas, if God is the cause of all that is, we can at least be sure that nothing can be the cause of God. This, says Aquinas, makes a radical difference between the way we love and the way God loves. For our love is caused by the goodness and attractiveness of what we love, but this cannot be the case with God. He does not love things or people because they are good; on the contrary, they are good and attractive because God loves them. God's love is creative; it brings about the goodness of what he loves. When, as it says in the beginning of the book of Genesis, "God saw everything that he had made, and indeed, it was very good" (Gen 1:31), God was not discovering its goodness. He was not struck with admiration by its beauty. Its goodness and beauty were his doing, the work of his love. For Aquinas, the entire universe, from each single raindrop to the furthest galaxies, exists because at every moment it is known and loved by God. The reason why God cannot love sin and evil is simply that "sin" and "evil" are not the names of things. They are defects, failures, nonbeing in otherwise good things. If I am sinful it is because I am failing to live up to what my humanity demands of me. I am failing to be just, kind, gentle or loving. I am failing to have that intense, passionate love for God's creation and God himself that would make me a fully developed human being. So God does not make sin and evil any more than he makes the elephant that is not in my garden. He makes all that does exist, and makes it by love: 

Everything that exists is, as such, good, and has God as its cause. Clearly then God loves all things, willing them every good they possess; yet not as we do. Our love doesn't cause a thing's goodness; rather the thing's goodness, real or imagined, evokes our love, and enlists our help in preserving and farthering that goodness. But God's love evokes and creates the goodness in things . . . God loves sinners as beings he has created, but he hates their sinning, which is a way of not being and is not God's doing. God loves everything with the same simple uniform act of will; but just as we love those persons more to whom we will greater good, even when we will it with no greater intensity, so too with God. God causes the goodness in things, and one thing would not be better than another unless God loved it more (ST la, 20, 2).

So God's love is at the center of every existing thing, the deepest reality in every existing thing. The special point about human beings, however, which is not shared by other animals, is that we can lay hold on ourselves, on the center of our being, by knowledge and love. Of course, other animals can know and love too, but not in the very profound sense in which we are able to do so by our capacity for symbolizing and articulating our world in language. Because we have this capacity to understand and to love, God can give us the capacity to respond to his love at the center of our being. God strengthens our understanding by the gift of faith and strengthens our loving by the gift of charity, so that we share in his self-understanding and in his loving. It is true that our share in God's self-understanding does not yet make God clear to us—that is something we are promised for the future. For the present, faith is more like a darkness. But we walk confidently in this dark, for we have learned not to put our trust in the specious and beguiling lights which fall short of the truth of God.

Faith is only the beginning of our sharing in God's self-knowledge, in God's Word, and, as St Paul tells us, it will pass away as it is transformed into the vision of God (1 Cor 13:8-12). But our sharing in God's loving, in that creative love in which he makes all things, our charity, will not pass away. The power to love as God loves, the power to share in his creativity, is the life we shall share for eternity.


Thomas Aquinas thought that God created a world with its own order, with its own natural causes within it. So we can explain the characteristic behavior of one sort of thing by referring to the behavior of another kind of thing within creation. Magnetic needles point to the north because of the earth's magnetic field, and in its turn, a magnetic field is caused by the behavior of subatomic particles.

These are not, of course, Aquinas's own examples, but, like most of us, he thought that there were causes in this world, and causes of these causes—a sort of hierarchical order of causes (like a chain of command). And this whole explanatory order, he thought, was created and sustained in being by God. He also thought it was the business of the natural sciences to trace this order of natural explanations (to show how the universe explains its own character). For this reason, he thought that there was no need for scientists to bring God into their scientific explanations. God is simply presupposed to be at the heart of the existence of the whole world that the scientist studies. It is quite true that God causes the kettle to boil, as he causes everything, but the scientist is interested in the natural created causes that God uses to bring about this effect. Physicists may well be driven to ask, "What is the explanation of there being anything at all instead of nothing at all?," but if they ask this, they are no longer doing physics. Aquinas would have been surprised and amused by the idea that in studying what seems to have happened in the first moments of the Big Bang we are somehow studying the act of creation. The creative act of God is not, for him, something unique to the beginning (if there was, indeed, a beginning), but to the continuing existence of anything at any time. In fact, he thought that God could easily have created a world which never had a beginning. For him the creative act of God is at work within the working of every creature all the time.

What, then, does he think about miracles? He says that God's activity is deep within everything and that nature's activities are to be attributed to God working within nature. But Aquinas also thinks that God, if he wants to, can override created causes so that he himself produces their normal effects or effects beyond their power (ST la, 105, 6). So Aquinas didn't see miracles as God intervening to interfere with the world. God, thinks Aquinas, cannot literally intervene in the universe because he is always there—just as much in the normal, natural run of things as in the resurrection of Christ or in any other miraculous event. A miracle, for Aquinas, is not a special presence of God; it is a special absence of natural causes—a special absence that makes the perpetual presence of God more visible to us. Since God is there all the time, and since he doesn't need to be mentioned when we are doing physics or biology, or doing the shopping, we may be in danger of forgetting him. So a miracle, in Aquinas's view, is an exuberant gesture, like an embrace or a kiss, to say, "Look, I'm here; I love you," lest in our wonder and delight at the works of his creation we forget that all that we have and all we are is the radiance of his love for us.


What is it to be a good person? What is it to live well rather than badly? We might say, "It is to act in accordance with some true moral code." If we are Christians or Jews, we might mention the moral code of the ten commandments. If we say this, however, we will find at least one person who disagrees with us, and that is Thomas Aquinas. He did not think that living well consists in acting in accordance with the commandments. This is not because he thought (as some modern Christians do) that the commandments have been superseded by the law of love. He thought the ten commandments were just a common-sense account of what loving behavior is like (and especially what it is not like). He thought that any society which was indifferent to whether you broke the commandments or not couldn't be a community of friends. He thought these commandments were one of those things given to us by God in his revelation which we could have worked out for ourselves, if we thought hard and honestly enough about what a society based on friendship would be like.

But although Aquinas holds the moral code of the commandments in high esteem, he would still disagree with you if you said that living well is simply acting in accordance with the commandments. Why? Because, he says, living well is not just a matter of doing good things instead of bad things. It is a matter of doing them well, and that means doing them from the depths of your real character.

You may do an act of kindness, you may send a donation for the relief of famine, say, in Africa, because you have been momentarily swayed by television reporting or whatever, and that, of course, is a good thing to do. You may do it because you have been told that it is the right thing for a Christian to do. You may do it because you fear that God will punish you if you don't, and it is still a good thing to do. But Aquinas would say that this is still not what living well means. Living well means doing good because you want to do it, because you have become the kind of you that just naturally wants to do this. Then you are no longer just doing kind acts. You are a kind person:

Living well is not only doing good things, but doing them well, choosing them in a right way and not simply acting on impulse or emotion. Right choosing involves having a right goal and suitably acting to achieve that goal. The dispositions to right goals are the moral virtues in the appetites; the disposition to act suitably to achieve the goal must dispose reason to plan and decide well, and that is the virtue of prudence. Doing something good on another's advice rather than one's own judgment is not yet a perfect activity of one's own reasoning and desiring. One does the good but not altogether well, as living requires. Thinking in a theoretical way seeks the true match of mind to things . . . Thinking practically seeks the true match to right appetite, and that can only happen in . . . matters we have power to influence . . . So the virtues concerned with contingent matters are dispositions of practical thought: skill for making, prudence for doing. In the case of doing, man's practical reasoning makes plans and decisions just as his theoretical reasoning explores and arrives at conclusions, but then goes on to issue commands to do things, and that is its special role. If men made good decisions and then didn't implement them properly, reason's work would be incomplete (ST lallae, 57, 5-6).

So Aquinas thought we become good, we live well, by acquiring a character, a complex set of dispositions which incline us, first of all, to want good things (and to want greater goods more than lesser goods), and then to think well in a practical way (to be wise) about how to achieve these goods. These dispositions are virtues, and we acquire them normally by practice. First, we do good things because we want to please our parents or others, or because we want to follow some moral code. But, gradually, such behavior becomes second nature to us, and then, and only then, do we have the virtues. Then we are grown-up. Then when we do good actions they are our own, springing from the personality we have created for ourselves with the help of others. That's what education is, or ought to be.

But, of course, Aquinas thought that we are not simply called by God to live well as human beings, but to live the life of God; and this is the sheer gift of God. So God, besides giving us clues to guide us on our way to him, also gives us the power to make the journey. He begins to share his own life with us and so gives us the virtues we need to live well both humanly and divinely—and gives them as a free grace, bypassing the laborious educational process.


That great English Tory Dr. Johnson declared, "I have always said the first Whig was the Devil." That great English Whig (or Liberal) Lord Acton said, "The first Whig was not the Devil, but Thomas Aquinas." I am not sure that Aquinas would have been altogether pleased with that compliment. Certainly he had no time for Liberal free-market economics and unrestrained competition. He thought that it was the business of the state to care for all the people, especially the poor, and in some cases to intervene to decree maximum prices and minimum wages. He thought that the purpose of law was not just to protect people from each other, but to help them all to be virtuous and, therefore, most likely to be happy in this world. He would undoubtedly have welcomed the welfare state.

He would have disagreed strongly with Margaret Thatcher when she said, "There is no such thing as society, only individuals and their families." He was more subtle than that. He said that the individual is essentially a part of society, and that the good of the whole society is greater than the good of the individual. But he also thought that the whole society exists for the sake of the good lives of its individuals.

Aquinas was a Whig or Liberal in that he had no time for any notion of the "divine right of kings," or the divine right of the party, and would rejoice at the collapse of dictatorships. He said that the authority of rulers and their laws comes only from the consent of the governed, and he said that "planning for the general good belongs to the people as a whole, or to those who represent them" (ST lallae, 96, 4). He thought that a legitimate representative of the people, ruling with their consent and making laws for the common good (and not just for the good of this or that class or section within society), was ruling justly. In so far as he or she ruled justly, he or she ruled with the authority of God, but only in so far as he or she ruled justly:

Humanly enacted laws can be just or unjust. To be just they must serve the general good, must not exceed the lawmaker's authority, and must fairly apportion the burdens of the general good amongst all members of the community. Such just laws oblige us in conscience since they derive from the eternal law. Laws however can be unjust: by serving not the general good but some lawmaker's own greed or vanity, or by exceeding his authority, or by unfairly apportioning the burdens the general good imposes. Such laws are not so much laws as forms of violence, and do not oblige our consciences except perhaps to avoid scandal and disorder, on which account men must sometimes forego their right. Laws can also be unjust by running counter to God's good, promoting idolatry say; and nobody is allowed to obey such laws: we must obey God rather than men (ST lallae, 96, 4; quoting Acts 5:29 in italicized text).

Aquinas thought that an unjust society which discriminates against some section of the people on grounds of racism or ideology or religious bigotry, or any other grounds, is already a society of violence rather than law—long before any dissidents seek to overthrow it. Law, says Aquinas, is only just, and only genuine law, if it is an expression of morality. On the other hand, however, Aquinas did not think it the business of law to repress every immorality, for, he believed, this may often do more damage to the common good than tolerating a wicked practice. Here, said Aquinas, rulers must use their common sense, their wisdom, to decide whether or not some particular human behavior should be a crime. Aquinas, for instance, thought that abortion was sinful and a great human evil. But, when you have said that, you have not yet decided whether and how it should be forbidden by law. That is something Aquinas would think open to discussion amongst people all equally committed to the sanctity of all human life. Yes, perhaps he was the first Whig.


It would be quite generally agreed that the foundation of Chris­tian morality is that people should love each other. Thomas Aquinas, interestingly, did not agree. Of course, it depends on what you mean by "love." You can love your mother, good wine, your country and your boyfriend—each with a different kind of love. When it comes to love in its most fundamental sense, however, Aquinas thought that the author of the first letter of John had got it right: "In this is love, not that we loved God but that he loved us and sent his Son" (1 John 4:10). Love is, first of all, what God has for us; indeed this love is God. God loves us so much that he lets us share in his own power of loving. We have a special name for our sharing in God's power to love: we call it charity

This divine charity of ours, says Aquinas, is first of all our response to God's love for us. So first there is the mutual love which makes us friends with God, sharing in his life and joy. This is the foundation of Christian morality: not a code of con­duct but our friendship with God, or sharing in his Spirit, which shows itself in our love for God's friends and creatures. But our friendship with God, says Aquinas, surprisingly but profoundly, does not first overflow into love of others. First of all, he insists, we must love ourselves. If we do not love ourselves, we cannot love others. 

There is a kind of fake altruism in which we can busy our­selves with others because we fear that, if we really considered ourselves, we would hate what we see. But charity means that we are able to take a clear look at ourselves, warts and all, and yet love ourselves in charity as God does. This is not selfish­ness. Selfishness comes from loving not our whole selves but just that part of ourselves that is our bodily life and our bodily possessions (in which we can be in competition with others). In charity I am concerned for the flourishing and happiness of my whole self, including the health and strength and liveliness of my body, but not excluding even more important things like my attitudes to others: 

Strictly speaking we don't have friendship for ourselves but something more: a love of self which is at the root of all friendship, since in friendship we love others as we love ourselves. But charity is friendship first with God and secondly with all who belong to God including ourselves. So we love ourselves with charity, inasmuch as we too are God's. When we blame people for self-love it is be­cause they love . . . their bodily natures, not loving what is genuinely good for themselves as rational beings . . . Our bodies were created by God, not . . . by some evil princi­ple. So we can serve God with our bodies, and should love them with the charity with which we love God. What we shouldn't love is the taint of sin and the damage it has wreaked in our bodies; we should rather long with charity for an end of all that. Our body helps us to happiness, and that happiness will overflow into our bodies, so that they too can be loved with charity (ST, Ilallae, 25, 4 and 5).

Thomas Aquinas is a very long way from those people, in­cluding some Christians, who think that the body, and espe­cially our bodily pleasures and emotions, are to be feared and avoided. He thought that we must learn to love and take delight in our bodily life (as God does)—giving it its due place and dig­nity. For God loves our bodily selves not only as creatures but as personal friends. Aquinas says in one place that separation from God by sin has so distorted our emotional life that we do not enjoy sex enough (ST Ia, 98, 2, ad. 3).

For Aquinas, it is only heretics who dislike and despise the body. For him the Word of God to us is not, first of all, words in a book. It is the Word made flesh, through whose body and blood we are brought back to friendship with God, so that at the resurrection of the body the divine life will overflow into our bodies in eternity. 


Not very many people can claim to understand just where physics is going nowadays, but sixty or so years ago we were hearing that the behavior of things depended on their atoms, and that atoms consisted of rings of electrons spinning around a nucleus. Each atom was a bit like a tiny solar system, and the familiar visible goings-on in the world were more or less deter­mined by the structure of these revolving systems of particles. 

Remembering this may help us to understand how Aquinas, in the thirteenth century, saw the physical world. His picture was remarkably similar, except that the spinning objects that determined the laws of physics and chemistry, instead of being very much smaller than our familiar objects, were very much bigger. He inherited the ancient belief that the revolutions of the stars and the planets played much the same part as the modern spinning of subatomic particles: they accounted for the regular, predictable behavior of physical objects. Aquinas was quite wrong, of course, but his ideas about how far the stars determine happenings on earth remain, perhaps, relevant when we ask how far the mechanisms studied by modern scientists determine what goes on. 

Medieval people were almost as superstitious as modern peo­ple, and fascinated by "what the stars foretell." But Aquinas was very skeptical about all that. He thought that the stars could af­fect us physically, and so, like tranquillizers or alcohol or lack of sleep, could affect our emotions and feelings, and incline us to certain kinds of behaviour. Incline us, but not determine us, for we can stop and think, and we can deliberately cultivate patterns of reasonable behavior (virtues), so that we won't be dominated by the feelings of the moment. In this way we can escape slavery to the stars (so Aquinas thought). 

Nevertheless, because a great many people don't bother to think or to learn how to be reasonable, they are swept away by their feelings and prejudices. That, Aquinas thought, is why astrologers can often be right statistically about majority be­havior—rather like sociologists predicting (or at least explain­ing) trends or voting patterns: 

Clearly events which happen necessarily can be predicted with the help of the stars, in the way astronomers pre­dict eclipses. But the stars neither signify nor cause future chance events . . . Nor can the stars cause free acts of rea­son and will; bodies cannot directly affect our mind and will, which are neither bodily nor functions of bodily or­gans. The stars can cause changes in human bodies, and so influence our sensual desires which are functions of bod­ily organs. So the stars can incline us to certain behaviour. But since . . . our sensual desires obey reason, man still has a free will to act against the influence of the stars. So, try­ing to predict chance events or human behaviour from an inspection of the stars is pointless . . . This doesn't preclude prediction of things which are truly effects of the stars, like drought and rainfall and suchlike. Moreover, the stars cause changes in our bodies and influence our emotions, and since most men follow their emotions without con­trolling them, astrologers often get things right, especially when predicting group behaviour (ST Ilallae, 95, 5).

For Aquinas, the constant movement of the stars, and the regular behavior of nature governed by this, is the work of God the Creator. But the works of human intelligence are an even greater manifestation of God's power. The things we do because we decide to do so for our own reasons (and not because we are the playthings of physical causes), these free acts, are not brought about by any created things, but are directly created by God. 

So Aquinas did not think that our freedom makes us indepen­dent of God's creative energy (nothing that exists could be that). But it makes us independent of other creatures. For Aquinas, we can stand over against all the forces of nature because of the creative work of God within us. We are free not in spite of God, but because of God. So human freedom, human creativ­ity, is the greatest manifestation in the world of God's creative love—except for that most free of all human beings, who was himself God's love in the flesh amongst us. 

Reprinted with permission from Bloomsbury Publishing, Plc
©The Estate of Herbert McCabe OP 2007
Excerpted from Faith Within Reason.

Featured Image: Carlo Crivelli, St. Thomas Aquinas, 1476; Source: Wikimedia Commons, PD-Old-100.


Herbert McCabe

Herbert McCabe was a Dominican Friar and theologian of outstanding originality who died in 2001. He was deeply influential on philosophers such as Anthony Kenny and Alasdair MacIntyre and poets and writers like Terry Eagleton and Seamus Heaney.

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