We are accustomed to sum up the Christian doctrine of the Trinity in the Latin formula derived from Tertullian, three Persons in one substance. Greek theologians confess three hypostases but one ousia. The last two words, whatever their precise meaning, are clearly authorized by the Nicene Creed – both the original version of 325 and the customary version attributed to the Council of 381 – which states that the Son is homoousios with the Father; the word can be rendered in Latin form either as ‘consubstantial’ or as ‘coessential’. But problems arise from the fact that the Latin word essentia, which is the exact equivalent of ousia, fell out of use. Latin theologians therefore translated ousia by substantia which is etymologically equivalent to the Greek ‘hypostasis’. The Latins thus used substantia to express the divine unity; the Greeks used the corresponding word to confess three hypostases: Father, Son and Spirit. Consequently the Greeks were liable to suppose that the Latin una substantia (like ‘one hypostasis’) denies the Trinity. The Latins, conversely, could suspect the Greeks of preaching ‘three substances’, three distinct or different Godheads. Nor was this merely a difference of technical terms; both sides were to some extent influenced by their own terminology, so that at important moments the Latins were inclined to put their main emphasis on divine unity, the Greeks on a clearly articulated Trinity.

The word homoousios has been much discussed; but the traditional explanations are unreliable. We begin by considering its constituent parts. First, the prefix homo- suggests unity or togetherness; but its sense is not perfectly constant.

The previous chapter has alluded to problems which arose from an imperfect understanding of the terms ousia and hypostasis. In the West Tertullian's formulation una substantia, tres personae was accepted by thinkers whose theological interests were perceptibly different from his own; whereas Tertullian was anxious to uphold the distinct existence of all three Persons, his Roman contemporaries and successors laid more stress on the divine unity. In the East there was no agreed formula, and tensions were sharper. Many Easterners reacted strongly against modalist teaching. Origen spoke of three hypostases, partly in order to maintain the substantial reality of Son and Spirit; but the phrase came to suggest his distinctive trinitarian teaching which ranked the three Persons in a descending scale of dignity and power. Some Easterners, either to avoid this implication or in imitation of Western usage, spoke of ‘one hypostasis’; but this again could suggest that only the Father is substantially real, the others being only his energies or functions. In the heat of theological debate there was little concern for reflection on the terms employed. Theologians drew no clear distinction between hypostasis and ousia, though there was some difference of nuance. Origen's use of the latter term was not clear-cut. Later Origenists thus disliked the term homoousios, which seemed uncomfortably close to the much-detested ‘one hypostasis’; but they were not unalterably opposed to it; a hard-line insistence on three ousiai remained a rarity.

In a review-article in IPQ, (1989) of O'Connell's book on The Origin of the Soul in St Augustine's Later Works I was puzzled as to why, if Augustine's final position on the origin of the human soul is neither traducianist (the soul as well as the body is handed down from one's parents) nor creationist (individual souls are constantly being created by God), these two rejected hypotheses are still apparently on the table until the end of Augustine's life (e.g. Incomplete Work 2.177–181). O'Connell thinks not only that Augustine was unprepared to be too dogmatic, but that as a wary ecclesiastical campaigner he was concerned not to give a handle to dangerous opponents.

Augustine at least ‘knows’ that our souls all shared Adam's sin, so that what he expresses ignorance about is not ‘our’ existence ‘in Adam’, but only how, after existing in Adam, our souls arrived in our present bodies. Yet it is still strange that creationism is not rejected outright, for it implies the making of new (and therefore guiltless) souls. Now it is true, as O'Connell regularly notes, that creationism was a very popular Christian belief outside North Africa. (Both Jerome and Pelagius subscribed to it.) So it may be that, since Augustine can find no knock-down scriptural text or reasoned argument against it, his profession of ignorance merely reflects an unwillingness to condemn a position so widely and traditionally held. Compare his unwillingness to condemn women who had committed suicide to avoid rape, because he knew they had been honoured in the Church as martyrs.

Augustine knows (and tells Jerome in Letter 166, for example) that squaring creationism with original sin is peculiarly difficult.

In The Master (2.3) Augustine quotes the following line from Virgil:

When Augustine's son Adeodatus is asked how many signs the line contains, he replies Eight – surprisingly if his father is supposed to be availing himself of Stoic theory. Thus he seems to assume that each individual word is a sign but that the verse as a whole, or the proposition [if] ρ, does not signify or refer to anything further, that is, beyond what is signified by each of its parts. Nevertheless, commentators on The Master often assume that for Augustine sentences do have some signification beyond that of the individual words of which they are composed, and that Augustine follows, but does not state, let alone defend, a theory to that effect. In fact the commentators are right, but they do not know why they are right.

The theory derives from Porphyry, and Augustine probably acquired his familiarity with it from one of Victorinus' commentaries, either that on Aristotle's Categories or that on Cicero's Topics. It may be briefly explained as follows: when Porphyry decided, contrary to the view of his master Plotinus, that Aristotelian logic could be put to the service of Platonic metaphysics, he argued precisely that a proposition about the ‘ordinary’ world, which, prescinding from Platonic metaphysics, appears to make sense, consists of a subject plus a concept (noema, or ennoia) which indicates the special and disambiguating features of the subject in each case. (If the concept is a second-order word (like a universal), it may be called an epinoia.)

THE HISTORICAL AND THEOLOGICAL SETTING

It must ever be impossible to detail all the factors which govern our attitudes to the society in which we live or wish to live. Two, however, are obvious enough: firstly, the sort of world itself which surrounds us – to understand which involves us in historical investigations and explanations; secondly, the goals we propose for our own lives. In the case of Augustine the historical questions are complicated by the unusual events of his own lifetime: not only, though importantly, the establishment at the end of the fourth century of Catholic Christianity as the official religion of the Roman Empire, a process accompanied by the active suppression of other forms of Christianity and a concerted attack on pagan temples, rituals and cults; but also far-reaching geopolitical changes within the social structure of the Roman Empire as a whole. Whereas at the beginning of Augustine's lifetime, and indeed during the period of his youth and of his years in Italy, the Roman imperium still seemed fixed and more or less unchanging, from the early fifth century the foundations of that society itself were shaken by barbarian onslaughts – Rome itself was briefly ruled by Alaric's Goths in 410 – and by factionalism and separatist pressures from within. Hence came an increasing decentralization, a fragmentation of the imperial power and a decline in the prosperity of the cities which formed the building-blocks of the Empire itself.

Augustine was a Platonist before he was a baptized Christian, and he was an admirer of Cicero before he was a Platonist. From Cicero and from his rhetorical training and teaching he acquired a concern that was theoretical as well as practical with words as tools of persuasion, and hence an incentive to think about some long-standing Stoic and Epicurean disputes about the nature of signs, verbal and otherwise: his knowledge of the matter may be said to be professional.

Augustine's treatment of signs is chiefly to be found in three works, two of which – plus a substantial part of the third – were completed within about ten years of his conversion: On Dialectic (387), The Master (389), Christian Teaching (begun in 396). On Dialectic was part of an early and abandoned project – a victim, according to Augustine, of the burden of ecclesiastical office – to show how the liberal arts can be harnessed to the service of Christianity: the theory presumably was that they all lead to and are measured by Truth, which is God (True Religion 31.57). As Augustine put it in the Reconsiderations (1.6), they can lead the student from the corporeal to the incorporeal ‘by certain definite steps’.

AUGUSTINE IN CONTEMPORARY SOCIETY

Augustine's body eventually rested in the now obscure Church of San Pietno in Ciel d'Oro in Pavia, but his influence remained alive and visible. Had he lived longer, he would have continued the contemporary debate about the quality of his own work. Suppose him to have been allowed to return to life in the late twentieth century to write his Reconsiderations over again. Suppose that, in so doing, he were not only to update his material where he found it necessary, but to persist with one of the principal objectives of the original work: to leave behind a set of writings from which the enemies of the Church, above all Pelagians of various stripes, could draw no comfort.

One of the reasons for the surviving historical influence of Augustine is that he escaped from his own philosophical past and bequeathed himself, apparently – but only apparently – without such a past, to his Western successors. But if Augustine's philosophical and theological strength derives in part from his comparative intellectual isolation, that isolation contributed in less happy ways to the reception of his writings and to the nature of his influence, both before and after his death.

LOVE AND INSPIRATION

Augustine learned from many sources, but his varied learning is often originally ill-digested and years later far from totally assimilated. When a degree of assimilation occurs, it may have been prompted by challenges which have arisen almost by chance. Especially in the decade or so after his conversion, Augustine was constantly driven to reassess what he had learned from the Greek philosophical tradition: from the Stoics and to a greater degree from the Platonists. For although he had learned from Plotinus how to surmount various forms of materialism, his experience of Christian life, first as a devout layman, and later as a priest and bishop, made him increasingly aware of new and hitherto unexpected ways in which the tenets and goals of Neoplatonism and Christianity are in conflict. Even at the time of his conversion, though believing Neoplatonism to be compatible with Christianity, he already held it to be incomplete.

We have already seen how Christian experience and biblical reflection affected Augustine's treatment of a series of traditional problems about the relationship of the soul to the body; but nowhere is Augustine's reassessment more evident, or more far-reaching, than in his account of moral behaviour and of virtue; and nowhere is it more acute than in his treatment of the Christian commandment to love one's neighbour.

It is not difficult to understand why love of neighbour presented problems for Augustine both at the philosophical and at the personal level.

INTRODUCTION

Augustine prays to understand God and the soul. But why not understand the human being? Or is the human being the soul? If the human being is not the soul but the soul and body, what is the relationship between the soul and the body? And why did Augustine not pray to understand the body as well as the soul? Full answers to these questions, involving as they do a lengthy investigation of the development of Augustine's thought from his conversion to his death, would require a series of detailed and technical discussions beyond the scope of the present study; yet some sort of answers are essential, for here if anywhere is the ‘core’ of Augustine's thought. Let us begin with two philosophical reasons why, in the Soliloquies, Augustine wants to understand the soul, rather than the human being, and then outline why he later concluded that there is an important sense in which it is not possible to understand the soul (or at least one's own soul) without knowing something of its body. Only then shall we find that his view of the relationship between the soul and its body has changed as well.

AUGUSTINE'S INTEREST IN SCEPTICAL ARGUMENTS

It is necessary to consider Augustine's treatment of scepticism for two reasons: historically it enables us to evaluate an important and ongoing aspect of his intellectual growth; philosophically it helps us to understand the claims he wants to make about the importance of belief as distinct from knowledge, and the priority of understanding to both. It is principally on Cicero's Academics that Augustine's writings on scepticism, and more generally on epistemology, depend. Such material was not available in the Neoplatonic texts with which he became familiar. His knowledge of Plato's Meno and Theaetetus was derivative, and he knew nothing of Aristotle's Analytics or of any Stoic or Sceptic epistemological texts in Greek.

We get to know, at least in part, by communicating with other people. Augustine's account of given signs shows that he held such communication to be flawed, but not impossible, in our fallen condition. Speakers are able to express at least part of what they wish to express, though hearers will not necessarily be able to understand them. If we want to pursue the matter further, therefore, we must consider the learning capacities of the hearer, or rather not only his learning capacities qua hearer (or reader), but more widely how Augustine supposed that he acquires beliefs, information and understanding of a variety of types of subject-matter.