The prehistory of Augustinian inwardness begins with the attempt to prove the immortality of the soul that Augustine presents as the crowning achievement of the Cassiciacum works. Augustine’s proof identifies Truth with the content of the liberal disciplines, on the grounds that dialectic is the Truth by which all truths are true. The key claim is that discipline, like Reason, is inseparably present in the mind, so that the immutability of Truth “rubs off,” as it were, on the mind, making it immortal. The failure of this argument is due to its insufficiently Platonist ontology, vitiated by lingering traces of materialism.
The crowning task of the Soliloquies is to prove that the soul is immortal. Augustine’s general strategy here is one that goes back to the Phaedo: he tries to establish a necessary conceptual link between the soul and that which is immutable and divine. He follows Plotinus rather than Plato, however, in locating the immutable and divine within the soul. Hence with this argument we see the earliest version of an Augustinian philosophical project that bears the marks of an encounter with Plotinus’s inward turn. It is not yet Augustine’s inward turn, nor even an inward turn at all, but it takes the fundamental first step of locating the immutable and divine within the soul. Hence in subsequent works he can conceive of seeking God there.
Augustine’s particular variation on the Platonist theme of the immortality of the soul is an attempt to demonstrate that the immutability of Truth, present within the soul, has a way of rubbing off on that in which it is present. The basic idea could have been suggested by Plato himself, who wrote in the Meno, “If the truth of beings is always in our souls, then the soul must be immortal.”1 But Augustine’s precise way of going about this demonstration is startling to the point of being bizarre and is quite unlike anything else in either Christianity or Platonism. We shall spend the rest of this chapter analyzing the structure of this astonishing argument, which was too bold and foolish to remain very long at the center of Augustine’s thinking. We can begin by looking at a striking identification made in the basic premise of the argument—an identification characteristic of Augustine’s whole procedure at Cassiciacum, and soon to be abandoned. The argument is initially stated as follows:
If whatever is in a subject abides forever, it is necessary that the subject itself also abide forever. And every discipline is in the mind [animo] as in a subject. It is necessary, therefore, that the mind abide forever, if the discipline abides forever. Now, discipline is Truth, and as the argument [ratio] at the beginning of this book demonstrated. Truth abides forever. Therefore the mind abides forever, nor can the mind be called mortal.2
This argument, which Augustine proceeds to elaborate and defend in the rest of the Soliloquies, is the culmination of all the inquiries at Cassiciacum, but it seems to have been passed over by most readers, who must have thought that Augustine cannot mean what he says. And reasonably enough: for it is hard to believe that anyone, much less a Church Father, could say that the liberal arts are God. But this is exactly the import of Augustine’s key premise here. He flatly identifies disciplina, the word for studies in the liberal arts curriculum, with veritas, the Truth by which every truth (verum) is true—which, as the previous discussions at Cassiciacum make clear, can be nothing other than God.3 This, together with the premise that the liberal arts reside permanently in the mind, yields the conclusion that the soul abides forever. The second premise may also seem surprising, since not everyone has been educated in the liberal arts, but Augustine defends it by alluding to the Platonist doctrine of Recollection: it may seem that the liberal arts are not always present in our minds, yet in fact knowledge of them does not come to us from without but rather is buried in our forgetfulness and “dug up” when we are reminded to do so by the right questions.4 Thus it is the first premise—the identification of discipline with Truth—that really needs an elaborate explanation and defense.
We must bear in mind that Augustine is exploring here. Representing himself as speaking only to God and to Reason, Augustine is writing the Soliloquies in order to find out what Reason, Truth, and the Soul are. He has ambiguities to clear up, and one way he does this is by trying out various ways of identifying such entities as “Reason” or “Truth” and examining their consequences. Let us try to imagine why Augustine thought the identification “discipline is Truth” might work. To begin with we can use a distinction that Augustine himself would supply a year or two later: that between signum and res, sign and thing signified.5 If we think of the liberal disciplines as a set of words (and hence of signs) that are heard by the ear or read in books, then the identification of God with the liberal disciplines is ridiculous—and quite abhorrent to a Platonist, for it would make God a sensible thing. But if we attend instead to the thing signified by the words, then we are brought into the realm of intelligible truths, and that is quite a different matter.
A concern with the truth signified by the words of the liberal disciplines is evidently what Augustine has in mind when he proceeds to argue that the disciplines are inherently true:
Discipline gets its name from discere, to learn. Now, nobody who learns and retains something can be said not to know; and nobody knows what is false. Therefore all discipline is true.6
Again, the argument is, on the face of it, bizarre: the basic premise amounts to the claim that one can never learn anything false. Either Augustine is convinced that no one can ever acquire false beliefs7 or else his premise ought to be read as a claim about the concept of “learning”: any learning worthy of the name means finding truth, not falsehood.8 The import of the premise would then be that in true learning we do not just come to believe that some sentence or other is true—as if learning was merely the acquisition of opinion not knowledge—but rather we catch sight of some intelligible truth.
If that is the meaning of the premise, then the really questionable part of the argument is the claim that the liberal arts actually consist of such learning. Why should we think that disciplina necessarily consists of discere, in this strong sense of learning to see the intelligible truth?
That this actually is the meaning of the premise is confirmed by the fact that Augustine laid the groundwork for his argument precisely by addressing the question: how can we say that everything in the liberal arts is true? The problem is that the liberal arts include not only mathematical disciplines such as geometry but also linguistic disciplines such as literature. As Plato warned, and Augustine the bishop later complains,9 literature consists mostly of fiction. How then can this, the first discipline to be studied in Augustine’s proposed curriculum, be true?
Augustine answers that the truth in literature lies not in the stories and fables of the poets but in the discipline that studies them.10 In effect, literary criticism rather than poetry is the sober guard of truth here. But that means the discipline of literature must draw its truth from some other source than the poetic fancies it studies. That source, Augustine insists, is another discipline, “the discipline of argumentation” (disciplina disputationis) which is concerned with definition and distinction and hence with separating true from false. This is plainly a reference to the discipline of dialectic. However, the name “dialectic” is not actually used in the Soliloquies, but rather a series of related descriptions such as disciplina disputandi, ars disputoriae, and ratio disputandi.11 This last phrase is especially interesting, as it plays into the open question of the identity of Reason in the Soliloquies. Ratio disputandi (literally, “the rationale or reason of disputing”) is not only an apt name for the discipline of dialectic but also a fine description of the Reason (ratio) who is Augustine’s inner dialogue partner in the Soliloquies. In addition, we should recall that Augustine would point out a few years later, in the essay “On Ideas,” that “reason” (ratio) makes a good translation of Plato’s word idea. Hence in calling dialectic by the name ratio disputandi, Augustine may be referring to something like the eternal Form that grounds or makes possible the temporal practice of argumentation—and it is surely not so odd to think that this might be Truth.
In any case, it is clear that one of the things Augustine is up to at this point in the Soliloquies is to explore the relation between Reason and the liberal discipline of dialectic. He is considering the quite plausible surmise that “the discipline of argumentation,” or what we today would call logic, teaches us something important about the essential nature of Reason. If we distinguish once more between signum and res (i.e., between the words one hears while being instructed in logic and the intelligible truth one grasps when one really sees the point) then it is quite plausible to say that the res, the thing signified by instruction in dialectic, is nothing other than Truth.
According to On Order, Reason is “the activity [motus] of the mind which can distinguish and connect what is learned.”12 It is precisely such activity that sets a discipline in order and guards it from falsehood—and dialectic is the discipline that teaches this activity.13 Hence Augustine has extraordinary things to say about the discipline of dialectic. It is
the discipline of disciplines ... it teaches how to teach and how to learn; in it Reason shows itself and manifests what it is, what it wants, what it can achieve. It knows how to know; it alone not only wants to make knowers but also can do it.14
This discipline of disciplines is the source of all other truths, distinguishing the true from the false in all other disciplines and connecting one truth with another within them.15 It is because of this function of dialectic that Augustine identifies it with the Truth by which all the disciplines are true. This is an identification for which Augustine had prepared us in the Cassiciacum dialogues, when he claimed that perfected dialectic is the very knowledge of Truth.16
Augustine’s argument is thus that dialectic, the discipline or ratio of argumentation, establishes what is true in all the disciplines, including itself; hence it is through its own self that dialectic is true—the point being that like the intelligible Sun, it shines by its own light, even as it lights up other truths and makes them capable of being learned. The identification of disciplina as a whole with Truth follows from this: discipline is Truth precisely because it includes within itself the discipline of argumentation by which all the disciplines (or discipline per se) is true. So we can say of disciplina as a whole what is said of the discipline of argumentation in particular: it shines by its own light.
Since the passage in which Augustine makes this argument is full of nuances and ambiguities that are difficult if not impossible to translate, I will quote it here in full, with commentary. The crucial ambiguity stems from the endemic problem that Latin lacks an indefinite article, so that it is often unclear whether the term disciplina in the singular means one of the seven liberal disciplines or “discipline” (i.e., learning) in general. There may indeed be a shift from one meaning to the other over the course of the argument, which is no insignificant matter, for the ultimate subject of the argument is not a plurality of disciplines but Discipline itself. Augustine’s aim is to demonstrate that Discipline itself is not just a collection of truths but the one Truth by which the many truths are true—the equivalent of Plato’s First Principle or Form of forms.
R: . . . You said, and said truly, that no discipline occurred to you in which it was not the law of definition and distribution which made it [a] discipline. And if they are true precisely by that which makes them disciplines [eo verae sunt quo sunt disciplinae] then would anyone deny that Truth itself is that through which all the disciplines are true?17
This line of reasoning rests on several latent premises as well as the two premises it makes explicit. The first sentence gives us the explicit premise that it is dialectic (the law of defining and distributing) that makes a discipline a discipline (ut disciplina sit, fecerit). The second sentence begins by laying down the crucial premise that what makes a discipline a discipline is the very same thing that also makes it true. From a previous argument we know that it is Truth (veritas) that makes every true thing (verum) true.18 Consequendy, it is Truth that makes the disciplines true. The conclusion (implied but not stated) is that dialectic, which makes the disciplines discipline, must be none other than the Truth that makes them true.
“Augustine” finds this reasoning persuasive, but he hesitates. For isn’t dialectic itself just one of the many disciplines, as much in need of Truth as the others?
A: I am quite close to assenting, but this is what bothers me: we count the ratio of argumentation too among these same disciplines. That is why I rather consider that to be Truth by which this very ratio is true.
R: An excellent and very alert answer. But I don’t suppose you deny that it is true precisely by that which makes it [a] discipline?
A: On the contrary, that’s exactly what’s bothering me. For I observed that it too is [a] discipline, and that’s why it is called true.19
“Augustine” has seen all the essential points. He just needs to realize that dialectic’s job of making the disciplines true is reflexive. Dialectic does for itself the same thing it does for the other disciplines: applying the rules of distinction and logical consequence to itself, it make itself true. That means that dialectic itself is the Truth by which dialectic is true.
R: Well then, do you think there is any way this could be [a] discipline, if everything in it were not defined and distributed?
A: I have nothing more to say.
R: And if this job [officium] belongs to it, then it is through itself that it is [a] true discipline [per seipsam disciplina vera est]. Therefore, who will find it surprising if that by which all things are true is through itself and in itself the true Truth?20
In translating this I have adopted the most natural interpretation of Reason’s conclusion, taking dialectic (i.e., ratio disputandi) to be the unexpressed subject of the clause per seipsam disciplina vera est. But this clause could also be read as providing its own subject, in which case it should be translated: “discipline is true through its own self.” In that case the conclusion is that not merely dialectic, but discipline itself is Truth. This conclusion too could be supported by Reason’s line of argument, which implies that Discipline in general is true by virtue of something internal to it, namely, the discipline of argumentation. Precisely because the discipline of dialectic makes all the disciplines true, Discipline in general makes itself true. Thus it seems that if dialectic is Truth, then Discipline also is Truth—and Augustine has succeeded in justifying the premise he needs for his proof of the immortality of the soul.
Though the identification “Dialectic is Truth” is on the face of it bizarre, it does seem clear that Augustine seriously intends to say that what we learn in the liberal arts is that very same Truth that is God. The really odd thing is the tight connection between the liberal arts and ultimate Truth—but this would not seem so odd to anyone working in the tradition of Plato’s Allegory of the Cave, as I have suggested earlier.21 If the project of learning to see God through a program of education appears absurdly pagan for a Christian writer, three considerations may lessen that appearance. First of all, Augustine is not the only Church Father to have suggested it.22 Second, Augustine proves willing to be flexible about the kind of education involved: in his mature works Christian teaching replaces the liberal arts (Christian doctrina, as it were, steps into the place once occupied by liberal disciplina), but the notion that learning leads us to divine Truth remains.23 Finally, the Truth that Augustine wants to learn is, as always, Christ, who is also probably the same as the inner teacher called Reason in the Soliloquies,24 and whom Augustine calls “the discipline of God.”25
Augustine’s early attempt to prove the immortality of the soul in the Soliloquies becomes the model for a whole series of kindred proofs in the first part of his treatise On the Immortality of the Soul (sections 1-8), the immediate sequel of the Cassiciacum dialogues. It is in fact the rough draft or sketch of a planned third book of the Soliloquies, which Augustine never worked up into dialogue form. He had no intention of publishing it in the form we actually have it, but it fell somehow into the hands of people who circulated it against his will. The book is not much fun to read. As Augustine himself says, “Because of its abbreviated and convoluted reasoning it is so obscure that even my own attention flags as I read it, and I myself can scarcely understand it.”26 What we have in this treatise is the bare outlines of arguments: collections of premises and conclusions, objections and refutations.
It is clear, however, that the arguments sketched and defended here are modeled on the proof for the immortality of the soul in the second book of Soliloquies. The basic strategy is to locate something intelligible and therefore immutable in the soul (for example disciplina, ars, ratio, or verum), and then insist that whatever contains an imperishable thing must itself be imperishable. So, for instance, the opening sentence of the treatise presents the following set of premises:
1. Discipline exists somewhere.
2. Discipline can only exist in something that is alive [i.e., in a soul].
3. Discipline exists forever.
4. Something in which that which exists forever exists, cannot but exist forever.27
The conclusion at which these premises aim is plain: the soul in which discipline exists, exists forever. The most obvious objection to this line of argument, that the soul can be ignorant of the disciplines, is handled once again by a line of reasoning that goes back to Plato’s theory of Recollection:
But when we are reasoning with our own selves [as in the Soliloquies!] or else being questioned well by someone else about some of the liberal arts [e.g., in Socratic conversations such as Augustine presents in the other Cassiciacum dialogues] then what we discover [invenimus] we discover nowhere else than in our own mind. For to discover something is not to make or to generate it; otherwise the mind would generate eternal things through temporal discoveries (and it does discover eternal things: for what is as eternal as the principle [ratio] of a circle, which is grasped as never having a time in which it did not exist or will not exist?) So it is obvious that the human mind is immortal, and all true reasons are in its secret places [omnes veras rationes in secretis ejus esse], although because of ignorance or forgetfulness it may seem not to have them or to have lost them.28
Augustine’s argument for the immortality of the soul clearly implies the divinity of the soul. For the crucial attribute of the intelligible things that Augustine locates in the soul is their immutability, and their presence in the soul makes the soul also immutable, at least in its higher or rational part. And for Augustine (as for all orthodox Christians of the time) immutability is the one attribute that is most clearly and certainly characteristic of deity, the characteristic that distinguishes God from everything else. According to Augustine’s argumentation in On the Immortality of the Soul, therefore, this attribute belongs also to us, or rather to our Reason. Consider some of the premises Augustine collects in the second chapter of the treatise and the conclusion he is driving at:
Reason either [1] is the mind or [2] is in the mind.
Reason is immutable.
[Therefore, if (1) is correct, then the mind is immutable.]
In no way can that which is inseparably in a subject remain unchanged, if the subject itself is changed.
[Therefore, if (2) is correct, then the mind is never changed, i.e., is immutable.]29
Therefore, whether Reason is the mind or is only inseparably in it, the mind is immutable. That is to say, the rational part of the human soul is eternal, just like the things to which it is joined in intelligible knowledge. For the intelligible and immutable things that we understand are not gazed at from a distance, as in Plato’s Allegory of the Cave, but are located nowhere else but in the rational soul:
The things which are understood [intelliguntur] are understood to be located nowhere else than in the very mind that understands them, for at the same time they are also understood not to be contained in space [non contineri loco].30
This is the fundamental point of departure for the development of Augustinian inwardness. Augustine forges the conception of the self as an inner space in order to have a place where these immutable and divine things are found. This version of the divinity of the rational soul is thus the conceptual forerunner of Augustine’s later talk of turning inward to find God.
The key notion here is Plotinian: what is found in the soul is nothing other than the intelligible world, the realm of Platonic ideas, eternal truths or rationes (as Augustine calls them) that we learn in geometry and the other disciplines. But specifying the sense in which Truth, Reason or Discipline is “in” the soul is a tricky conceptual problem that Augustine is not equipped to solve yet. That is, I suspect, the most important reason why the third book of the Soliloquies was never finished.
We can see why the main argument of the Soliloquies and its various elaborations in On the Immortality of the Soul were doomed if we look schematically at the basic structure of Augustine’s reasoning. Let X be Discipline, Reason, Truth, God, or anything else immutable and intelligible. The basic template, as it were, of Augustine’s various proofs for the immortality of the soul is approximately as follows:
1. X is immutable (or exists forever).
2. X is in the soul.
Therefore, the soul is immutable (or exists forever).
I have deliberately made this template a little too simple, in order to bring out the need for a crucial qualification that Augustine makes to the notion of “in” used in the second premise. Recall the objection, which Augustine has handled twice already, that the fact of ignorance seems to show discipline is not always in us. The point of that objection can be generalized: if Augustine’s argument is to work, X cannot be in the soul only part of the time, for then the soul could lose it and become mortal. X must be a necessary and inherent part or feature of the soul. It is not enough to say simply that it is in the soul; it must be inseparably in the soul. Thus when Reason introduces the basic rule of inference that underlies the various proofs in the second and third books of the Soliloquies, it includes this crucial phrase: “Don’t you agree that what is inseparably in a subject cannot remain if the subject itself does not remain?”31
This is where the argument goes fundamentally wrong. For if this rule of inference holds, and God or Truth is inseparably in the soul in this sense, then God cannot exist without the soul. This makes God’s existence dependent on ours: Truth cannot remain unless the soul remains forever. It is important to appreciate that this conclusion was as repugnant to pagan Neoplatonists as it was to orthodox Christians. Neither tradition could stomach a line of reasoning that makes ontologically higher things dependent on lower things—in this case, the intelligible world dependent on the soul. The fact that Augustine’s argument has this consequence is due not to his Neoplatonism but to his philosophical incompetence. He does not yet command the conceptual resources needed to make the argument work. By the time he does, he knows too much about the Catholic Church’s rejection of the divinity of the soul to pursue it any further.
Consequently, Augustine abandons his proof for the immortality of the soul. But, very significantly, he does not abandon his project of finding the intelligible Truth in the soul—that is what the inward turn is all about. So the question remains: in what sense of the word “in” is it true that “Truth is found in the soul”? To see the shape of the problem this poses for Augustine, we can look at the concept he started with but had to abandon. In what sense is Discipline or Truth inseparably in the soul, according to the arguments in Soliloquies and On the Immortality of the Soul? And how, moreover, is this so different from the sense in which Plotinus could affirm that the intelligible world was in the soul?
Augustine approaches the problem by contrasting two ways we can say that something is in another thing. The first is the sense in which material objects are located in space, “such as this piece of wood in this place, or the sun in the East.”32 The other is the sense in which essential properties are inseparably in their subjects, “such as the form and appearance [forma et species] which we see in this piece of wood, or light in the sun, or heat in fire, or discipline in the mind.”33 This sense of “in” is one that “Augustine” claims is familiar to him from his school days.34 It comes in fact from the one text of classical Greek philosophy that Augustine ever mastered firsthand (even if in translation), Aristotle’s Categories.35 Augustine is claiming that intelligible things are in the mind the same way a quality is in a substance as its subject. Thus God is “in” the soul in the sense of the word “in” defined by Aristotle’s notion of a quality being “in” a subject: “By ‘in a subject’ I mean what is in something, not as a part, being incapable of existing separate from what it is in.”36 From a Platonist standpoint, this is a disastrous way to think about intelligible things, as it makes them ontologically dependent and secondary. The category of substance, for Aristotle, is ontologically primary, and the qualities that inhere in a substance (like color in a visible body, for instance) are ontologically dependent on the substance they are in.
Thus the philosophical concept Augustine uses to articulate the sense in which Truth is “in” the soul makes Truth ontologically dependent on the soul rather than the other way around. This is simply inept. For what Augustine obviously wants to do in his proof for the immortality of the soul is to show how the inherent imperishability of Truth “rubs off” on the soul in which it is present. His whole argument is therefore designed to show that the soul is dependent on Truth for its being, life, and immortality—not the other way around! Truth is supposed to endure even if the whole world were destroyed.37 Yet the implication of Augustine’s use of the phrase “inseparably in” is that without the soul as its subject Discipline or Truth cannot exist, for “that which is inseparably in a subject cannot remain if the subject itself does not remain.”38
It is useful to compare this failure, this conceptual crudity in the prehistory of Augustine’s inwardness, with the sophistication and subtlety of Plotinus’s use of the little word “in.” His use is largely metaphorical—and Augustine seems to have grasped the metaphor without quite grasping its limits. Much of the argumentation of Augustine’s On the Immortality of the Soul makes more intuitive sense if we keep in mind the powerful Plotinian picture of a cosmos composed of concentric spheres.39 At the center of everything is the One, from which radiates the intellible world or Mind, around which the sphere of the Soul metaphorically revolves (either turning inward to contemplate intelligible things or looking outward to fall among bodies). The sensible world or material cosmos, the world of bodies, is furtherest out from the center. The word “in” applies literally only to this last sphere, for only the world of bodies is actually spatial in its mode of being, and only in space can one thing be literally in another. Hence Mind is not literally “in” the soul, nor is the soul literally “in” the body. Rather, the metaphor of “inward” and “outward” represents ontological similarity and dependence—the more inward things are, the greater their resemblance to the ultimate One at the center of the universe, while the farther out they are, the more they suffer division and manyness (as the divine Mind is more diverse and variegated than the One, and bodies are the least unified of all, being divisible in space, capable of literally falling apart). Thus in order to drive home the point about ontological dependence, Plotinus is perfectly willing to reverse the metaphor and say that lower things have their existence in higher things—for example, that body exists in soul and soul in the divine Mind.40
This reversal also has the implication that lower things are not really distant from higher things. Separation in space is only possible in space, after all. Therefore nothing is ever literally outside the intelligible world, and nothing is ever separated from it by spatial distance. Rather, the intelligible world is omnipresent: the whole divine Mind is present undivided everwhere in the material cosmos. Transcendence thus implies immanence: precisely because the intelligible is not limited by a spatial mode of being, it is present everywhere in space, in a way impossible for material objects, which are necessarily spread out part by part in space and contained in one place rather than another. Hence for Plotinus, the fact that the Divine is not a bodily thing is precisely what makes it more fully present in the material world than bodies themselves are. Even in the sensible world, immaterial being means more being, not less—fullness of presence, rather than the partial absence that is the necessary mode of being of bodies, which cannot be present one place without being absent in another.
The Plotinian doctrine of the omnipresence of the intelligible in the sensible is to play a major role in Augustine’s thought, as we have already seen.41 Soon Augustine will even toy with Plotinus’ counterintuitive talk about the body being “in” the soul rather than the other way around.42 But at this point it is clear that he has not quite seen the full import of Plotinus’s complex way of relating the sensible world to the intelligible, because his whole argument depends on Truth being absent from every place but the soul. If Truth exists also outside the soul, then the claim that it is inseparably in the soul, in the sense Augustine specifies, is undermined. Thus, in striking contrast to his latter views of the integral omnipresence of Truth, Augustine affirms that Truth does not exist anywhere in space (non . . . in loco) or in bodies (non . . . in rebus mortalibus).43 Yet, Augustine insists, it has to exist somewhere, for “everything that is, must be somewhere.”44 This is precisely what a well-informed Neoplatonist would not say about the intelligible things. The intelligible exists everywhere in space, being omnipresent, precisely because it is not dependent on having any particular place or “somewhere” in which to exist.
Augustine soon realizes his mistake. Within a few years he asserts that “God is not somewhere” (Deus non alicubi est) and thence draws a conclusion that fits with Plotinus’s reversal of the usual language of inside and out, saying, “All things are in Him.”45 From this point onward, when Augustine says that God does not exist in a place, he does not mean that God is absent from any place but that his mode of being is non-spatial and therefore he is omnipresent. This realization dooms the proof for the immortality of the soul that was the main line of argument in the Soliloquies and its sequel.
It is worth seeing exactly why. What does this realization change? If God is not somewhere, then the dictum “everything that is, must be somewhere” is false. Now where did that dictum come from? Certainly not from Plotinus. It is the sort of thing a materialist would say, and in fact it came to Augustine from the Stoics, via Cicero.46 Variants of it recur in On the Immortality of the Soul,47 where it is needed to establish the claim that intelligible things, not being located in space, have nowhere else to exist but in the mind.
The diagnosis, therefore, is that Augustine’s argument fails primarily because it is insufficiently Neoplatonist. It is vitiated by his reliance on materialist concepts that he learned long before he encountered the books of the Platonists. More positively, we could count this abandoned proof of the immortality of the soul as a step on the road toward overcoming his old carnal habits of thought and formulating a fully Platonist ontology. In any case, what we cannot do, if we care to understand Augustine’s explorations here, is make apologetics for him by supposing that this is merely an example of “Augustine’s early Platonism,” which will be overcome by his deepening Christian faith.48 Rather, it is an example of old materialist habits of thought still infecting his newborn project of achieving a Christian Platonist view of God and the soul. It is doomed to be left behind because it is neither Christian nor Platonist enough.