1. TIMAEUS AND ZENO ON WORLD PRINCIPLES

It will be helpful to begin by briefly reviewing the salient similarities and dissimilarities between the physical theory of the early Stoics (as first articulated by the school's founder, Zeno of Citium) and the account of the generation of the physical cosmos offered in the dialogue by Plato's character Timaeus.

The Stoics posit two fundamental principles or ἀρχαί of the cosmos, an active one identified with ‘god’ and a passive one identified with ‘matter’. The Stoic active principle or god bears a significant resemblance to the World Soul as described in the Timaeus (see especially 36d–7c). Both the Stoic god and Plato's World Soul are held to extend throughout the body of the cosmos, and to encompass it all around. Both possess reason, and both govern the circular motions of the heavens by virtue of this reason. Both are said to cognize in a reliable way the things that they come into contact with. In sum, the two entities clearly resemble each other in so far as both are immanent ordering principles thoroughly pervading the body of the cosmos.

The Stoic passive principle resembles the Receptacle of the Timaeus, in particular as it is discussed at Tim. 52a–d. Here the Receptacle is characterized as a ‘room’ or ‘space’ (χώρα) on which physical qualities come to be imposed. This characterization is reinforced by analogies to gold, to liquid bases for perfume and to wax, all of which take on various imposed shapes and qualities.Footnote ² The similarity of this notion to the Stoic conception of matter is clear: on both accounts there is a pliable and controllable passive or ‘material’ component to physical objects.Footnote ³

The analogy between the roles played by god and matter in Stoic physics and those played by the World Soul and the Receptacle (respectively) in Timaeus' account is, however, imperfect; notably, Timaeus sees the need to appeal to further fundamental principles beyond these two in order to explain the physical universe. Although the World Soul perpetuates the grand order of the cosmos, that order is designed and established in the first place by the Demiurge, who is represented as existing separately from (and prior to) the cosmos.Footnote ⁴ The Stoics instead ascribe both functions to their active principle or god, although it is immanent within the cosmos; the early Stoics indeed appear to have used the term δημιουργεῖν to specify the activity of their active principle (Diog. Laert. 7.134). They see no need to separate the two spheres of responsibility as Plato does.

An even more pressing difference is the absence from the Stoic picture of any entities that correspond to the Platonic Forms. In the Timaeus the Forms constitute the unchanging incorporeal model that the Demiurge consults in his construction of the physical world, and so they are (it seems) crucial to the dialogue's account of the character of physical reality. The Stoics do not think there are such things as Forms, and their active principle exercises control over the various parts of the world not by shaping them to conform to a model that is ontologically privileged, but rather through application of its own inherent standards of rational order. And so the question of how Plato influenced Stoic physics turns, in large part, on the question of how Zeno and other early Stoics could appropriate the physics of the Timaeus while regarding the Forms as an inessential (or at any rate disposable and replaceable) aspect of that physics.

There are, I suggest, two distinct (but compatible) sorts of answers to this question that are both worth canvassing. The first takes its start from the exegetical practices of Zeno's contemporaries. We know that there was a great deal of interest in the Timaeus among the philosophical schools of Athens in the late fourth/early third century b.c.,Footnote ⁵ when Zeno would have become acquainted with the work. As a number of scholars have recently shown, a prominent line of interpretation of the dialogue that emerged during this period aggressively de-emphasized (and perhaps even elided altogether) the role played by Forms as causal principles in Plato's physics.Footnote ⁶ It is within this context, for example, that Theophrastus is able to report:

It is quite possible that Zeno was influenced by some such contemporary interpretations of the Timaeus.Footnote ⁸

The second sort of answer, which has received very little direct attention from scholars, looks to Zeno's own core philosophical commitments as forming an interpretive context for the Timaeus. It is plausible to believe that Zeno's thinking about principles or ἀρχαί developed closely in tandem with his basic ontological views. In adopting as the criterion of ‘being’ the ability to act or to be acted upon,Footnote ⁹ and in positing that only bodies meet this criterion, Zeno already lays much of the groundwork for – and significant constraints on – his doctrine of the principles of the cosmos. That is, if the only mode of being is being a body, for the reason that only bodies can act or be acted upon, then what is wanted from a theory of physical principles is precisely an account of what fundamental bodies can be held causally responsible for all physical phenomena.

There might be a variety of accounts that could be given along those lines, but it must be admitted that Zeno's account fits his ontology with an unmistakable straightforwardness and economy: he analyses physical bodies into two distinct but inseparable principles, both bodies themselves, one of which does all the acting and the other of which undergoes all of the being acted upon. The states that all physical items are in, and the changes that they undergo, are ultimately referable to these two principles, active and passive.

If this suggestion is plausible, then we may suspect that for Zeno the immediate interest of the Timaeus did not lie in its account of the ἀρχαί of the cosmos (including the Forms); for the general contours, at least, of Zeno's account of ἀρχαί were laid down by his own ontological views. Rather, he may have been primarily interested in the model that the dialogue offers of how his own two principles could be related to each other. For the Stoics, what ultimately explains how the active principle disposes the passive principle that it pervades – much as the World Soul pervades and controls the Receptacle – is the active principle's ‘demiurgic’ plan for how best to order the cosmos.

In sum, it seems that both contemporary interpretations of Plato and Zeno's own background philosophical commitments could well have led him to focus attention on the portrayal of the role played by the Demiurge – what Theophrastus above calls ‘the power of god and the good’ – in the cosmogony of the Timaeus.

2. TIMAEUS ON THE CHARACTER OF THE DEMIURGE

In the opening section of his speech (27d–29d), Timaeus places the physical universe into an explanatory relationship with an unchanging model via a divine craftsman who replicates that model to the extent possible in the changing medium of perceptible objects. What will explain the features of the perceptible, physical world are facts about how the craftsman – the Demiurge – caused it to be arranged so as to resemble (so far as possible) its model. Timaeus famously claims that by searching for this sort of explanation for the physical cosmos, we can construct a ‘likely story’ (εἰκὼς μῦθος) about it (a story that will make the cosmos intelligible to the extent possible, precisely because of its likeness to an essentially intelligible model).Footnote ¹⁰

What I would like to draw attention to is that Timaeus offers his audience only a minimal characterization of the cosmic craftsman. In fact, just two attributes are accorded to the Demiurge, attributes which are presented as jointly sufficient for him to do his work of producing the cosmos that we live in. First, he possesses reason (νοῦς),Footnote ¹¹ which gives him cognitive access to the realm of unchanging being. And second, the Demiurge is good, which motivates him to introduce beautiful order – such as belongs intrinsically to unchanging being – to the realm of changing and perceptible being.Footnote ¹²

These two attributes are left curiously unconnected with one another in Timaeus' speech. We might well imagine that the divine craftsman's goodness depends upon his apprehension of unchanging being via reason, but Timaeus offers no definite claim to that effect. Without making some further supposition about the relationship between the Demiurge's reason on the one hand and his goodness on the other, it is not possible to have a precise picture of the role that νοῦς plays in causing the cosmos to come into being. It is on the question of what such supposition to make, I suggest, that the Stoics are likely to have parted ways with other ancient readers of the Timaeus.

On the one hand, one might suppose that Timaeus takes the Demiurge's cognitive relationship to the realm of unchanging being – the Forms – to be precisely what makes the Demiurge good. The prologue of Timaeus' speech might be thought to offer some support for this view: the sign of the Demiurge's goodness is said to be his selection of the best model, the Forms, for the physical world (29a2–3). (A bad craftsman, it is implied, might well have forged a world too, but using some other and inferior model as a standard; and the world would consequently not be the beautiful cosmos that we live in.) On this view, our world is assumed to be the product of some creative impetus; but what is in fact good about this impetus (and what makes its product good or beautiful) is that it is directed by apprehension of the Forms.

Later Platonists, pressing this line of interpretation, would identify the Demiurge fully with νοῦς understood as cognition of the Forms,Footnote ¹³ and would go so far as to deny that the Demiurge can have any thoughts about the physical world as such. On this sort of account, the Demiurge is taken to be an intellect engaged wholly in contemplation of the unchanging Forms – or perhaps, rather, simply to be the living Forms' self-contemplation – and the material cosmos comes into being by emanation, as the necessary concomitant of such potent intellectual activity. The Demiurge so conceived cannot even think about the material and sensible realm, much less make plans regarding its disposition.Footnote ¹⁴ His goodness consists in his cognition of the Forms; that such cognition causes a well-ordered sensible cosmos to exist is a metaphysical fact, but not a fact that indicates any intent or concern on the part of the Demiurge.Footnote ¹⁵

The Stoics, on the other hand, conceive quite differently of divine reason and its relationship to the cosmos. They take god's reason to consist in deliberation about the material of the cosmos, and to yield explicit determinations of the best way for this material to be disposed. The formation and arrangement of the physical world is precisely god's practical implementation of his thoughts about the best order for matter to be in. His goodness on this view consists in his rational agency, as exhibited in beautiful cosmic order.

My suggestion is that this second conception of divine reason, even though it makes no reference to the Forms, can also be extracted from the Timaeus – and indeed, it can be extracted with surprisingly little difficulty. To do so, all that is required is to take Timaeus' account to have its proper beginning at 29d7, where he makes a fresh statement of the explanation (αἰτία) of the generation of the cosmos. Socrates himself explicitly marks this new beginning, interrupting Timaeus at 29d4–6. He thanks Timaeus for offering a fine ‘prelude’, and encourages him to commence what Socrates calls ‘the work itself’.Footnote ¹⁶ In rhapsodic and citharodic performances, the prelude or προοίμιον typically included an invocation and praise of gods; the presence of both elements at the beginning of Timaeus' speech (27c–d) may guide Socrates' choice of metaphor. What I want to draw attention to is the fact that the Stoics may have picked up on another implication of the same metaphor: that a performer's main song or νόμος is a semantically complete work, assessable quite separably from its prelude.Footnote ¹⁷

Accordingly, I propose to examine the following section of the speech in light of the hypothesis that early Stoic readers of the dialogue focussed on what they (perhaps following Socrates' cue) considered to be the proper beginning of Timaeus' main ‘work’: 29d–34b, where Timaeus represents the Demiurge as making and implementing reasoned determinations about the best way for the cosmos to be.

3. DIVINE PLANNING AS A CAUSE IN THE TIMAEUS

Timaeus begins his ‘work’ with the claim that the Demiurge's goodness is the key explanatory factor in the coming-to-be of the cosmos. The Demiurge is good, and so without jealousy, and so wishes all things to be ‘as like himself’ (i.e. good) as possible; this, we are told at 29e4, is the fundamental ἀρχή of the cosmos. The general consequence of this wish is that he takes charge of the perceptible realm and makes it orderly rather than disorderly, order being (he thinks) altogether better than disorder (30a2–6).

It is immediately after this point that the Demiurge is first represented as engaged in deliberative reasoning about the cosmos (30a6–c1). It is not permitted, we are told, for one who is supremely excellent (ἄριστος) to do other than what is best (κάλλιστον). So the Demiurge – being of such an excellent character – reasons that, in the realm of visible things with which he is dealing, what possesses νοῦς as a whole is better than what does not possess νοῦς; and further, that nothing (in this realm, at any rate) can possess νοῦς without possessing a soul. Having reasoned this out (λογισάμενος), he implements his reasoning (λογισμός) accordingly, forming the cosmos by investing it with a soul that possesses νοῦς. In this way, he produces a work that is best and finest. Therefore, concludes Timaeus, the likely account (which a physicist must affirm) is that the cosmos came-to-be as an intelligent animal διὰ τὴν τοῦ θεοῦ … πρόνοιαν. πρόνοια (‘forethought’ or ‘providence’) here evidently names the Demiurge's reasoned arranging of the cosmos.

Now, the relationship between this passage and that which immediately precedes it (30a2–6), where the craftsman's general preference for order over disorder is stated, is not entirely clear. Are bringing order to the visible realm and investing the cosmos with a soul two separate tasks for the Demiurge? Surely not entirely so; when the Demiurge acts on his plan of giving the world a reasoning soul, he is thereby imposing a certain sort of order on it. But we might think that the task of giving the cosmos a soul is in some way subordinate to the project of bringing order to it, perhaps merely one among many tasks involved in the Demiurge's overall project of introducing maximal order into the cosmos.

It is at least tempting, however, to go further than this and to read 30a6–c1 as specifying what the Demiurge does when he sets out to introduce order into the visible realm, i.e. how he goes about ensuring that the order he establishes is, indeed, the finest order. On this reading, what the Demiurge does, because he is good, is to reason about the best way for the cosmos to be, and to act accordingly. He reasons that the best way for the cosmos to be is to be an intelligent animal, and so he brings this about. In this case, Timaeus is telling us that divine craftsmanship is a matter of acting on reason's determinations about the best way for the world to be – that is what divine goodness amounts to. It is easy to see how, on this understanding, the Stoics would find this passage quite attractive. Indeed, it is surely not fanciful to suggest that the Stoics, taking the passage this way, adopted the term ‘providence’ (πρόνοια) directly from the Timaeus to designate their own active principle considered as the beneficent orderer of material in the cosmos.Footnote ¹⁸

4. THE CONTENT OF THE DEMIURGE'S PLAN

To recapitulate: on the basis of Timaeus' proem, we might have expected the divine ‘craftsman’ to be defined entirely by his relationship to his primary object of cognition, the unchanging model of the world. However, as soon as Timaeus begins to describe the actual formation of the cosmos, we find the explanatory emphasis of the account shifting to the craftsman as an agent who is providential in that he plans out how to make the best product (in this case, a world) that he is able to make.

As we have seen, the fundamental feature of the Demiurge's providential plan is that the world will be a living creature. In the passage which immediately follows Timaeus describes the formation of the world's body, to which its soul is joined to form a living whole (31b–34a). This passage describes the Demiurge as holding beliefs about how best to design this world body, and as engaging in διάνοια/διανοεῖσθαι and λογισμός/λογίζεσθαι about it, terms which typically (in Plato and elsewhere) indicate explicit or discursive reasoning. In the present context, they seem to designate what I have above called deliberating or the reasoning out of a plan.Footnote ¹⁹

Timaeus claims that the body of the world must be composed of four primary bodies (the elements), in quantities exhibiting a special proportion to one another, in order to be knit together in a suitably unified way (31b–32c).Footnote ²⁰ It is part of the plan that there should exist no amount of any element outside the cosmos – that is, the Demiurge plans to use up each element in its entirety in forming the world's body. In doing so, we are told, he has three intentions regarding this body (τάδε διανοηθείς, 32c8):

Summing up, Timaeus tells us that ‘on account of this cause and this piece of reasoning (διὰ δὴ τὴν αἰτίαν καὶ τὸν λογισμὸν τόνδε), he built it [sc. the cosmos] one and whole and complete, composed out of all wholes, free from old age and illness’ (33a6–b1).

I will not discuss the specific cosmological implications of each of these divine intentions towards the cosmos; I will note, however, that (1) and (2) are both somewhat puzzling. In (1), it is not clear in what sense an element (say, earth) is ‘whole’ just in virtue of being present in its total amount; neither is it clear how Timaeus thinks that wholeness or completeness applies to parts as distinct from wholes, in such a way that a whole can fail to be complete in virtue of one of its parts being incomplete. In regard to (2), surely we are not to entertain the prospect of a second (third, etc.) cosmic animal, such as is being described by Timaeus, coming to be outside of the cosmos without the Demiurge forming it. But in that case, what is the worry about leaving some elemental stuff outside the cosmos? Perhaps (2) is simply to be read as consequent to the requirement, stated earlier (31a–b), that the cosmos made by the Demiurge must be a unique copy of its unique model. Alternatively, it might be thought that (2) and (3) are intended to be taken together. Timaeus expands a bit upon the reasoning behind (3) as follows: in every animal, old age and disease are caused by the harmful influence of factors outside the organism. Removing all such external factors will render the cosmic animal immune to those conditions (33a3–6). So the thought behind (2) could be that (3), in specifying why it is best that there be nothing left over outside of the cosmos, explains why it is best that there be only one cosmos.Footnote ²²

A difficulty remains: neither of these interpretations explains why (2) expresses a worry about another cosmos arising, and not just a general worry about extra-cosmic stuff. I would suggest, as a plausible way of accommodating this as one of the Demiurge's distinct concerns, that Timaeus takes it that bodies left outside the cosmos by the Demiurge might well come to constitute another world. However, that new world would presumably be an inferior and less orderly cosmos, of the sort that the good craftsman would disdain to produce. So the Demiurge is motivated to include in his cosmos as much body stuff as possible – that is, all of it – so as to save what would remain from disorder, or at least from the relative disorder of an inferior cosmos. After all, we were told that the Demiurge's fundamental λογισμός about perceptible being is that order is better than disorder, tout court.

We are given further examples of divine reasoning in the passage immediately following this, where the cosmic body is given spherical form. This is the shape most appropriate to an all-comprehensive and everlasting animal, we are told, for two reasons. First, of all shapes the sphere is ‘most complete’ (τελεώτατος) and ‘most similar’ (ὁμοιότατος) to itself; and the Demiurge ‘considered that (νομίσας) the similar is immensely finer than the dissimilar’ (33b6–7). Second, the sphere is smooth all around. This is suitable for the cosmic animal because the animal is all-inclusive, so that it requires neither exterior organs to perceive what is outside of it nor orifices through which to breathe, take in food or discharge waste; its own waste is its nourishment. The animal was built ‘by design’ (ἐκ τέχνης, 33d1) to act and undergo all of its experiences itself within itself (33d1–3): ‘for its builder considered that if it were self-sufficient, it would be better than if it needed other things’.Footnote ²³ The Demiurge has a preference about the way the cosmos should be (self-sufficient), and he reasons out what shape will best implement this preference: one smooth all around.

As it happens, we know that the early Stoics were closely familiar with this section of the Timaeus, because we find Chrysippus drawing on it in a fragment from Book 1 of his On Providence preserved by Plutarch at Mor. 1052d (SVF 2.604): ‘The cosmos alone is said to be self-sufficient, because it alone has within itself all it needs, and it gets nourishment and growth from itself through the interchange of its parts with one another.’Footnote ²⁴

5. CONCLUSION: THE FURTHER PROVIDENCE OF THE WORLD SOUL AND OF THE YOUNGER GODS

Timaeus makes the transition from his discussion of the world's body to his discussion of the formation of the World Soul by summarizing the Demiurge's design of a body suitable for that soul (34a8–b2): this was the god's plan (λογισμός θεοῦ), reasoned out (λογισθείς) concerning the god-to-be – that is, the ensouled cosmos. In what follows (34b–37c), the emphasis is no longer on the Demiurge's planning, but on how the cosmos itself possesses and exercises reason. The World Soul is given an elaborate structure and a set of innate movements that make it perfectly suited to be the soul of a reasoning animal; the result, we are told, is that it shares fully in λογισμός (36e6) and νοῦς (37c2).

For later Platonists, this characterization of World Soul left behind some complicated questions: if the cosmos itself possesses the cognitive abilities and virtues of the Demiurge, what role is left for the latter? Is the Demiurge to be identified with the reason of the World Soul? If so, what sense can be made of Timaeus' elaborate account of how the Demiurge fashions the World Soul? And if not, what exactly is the relationship between the two? The point I want to make is that the text does offer a clear temptation to identify the Demiurge with the νοῦς of the World Soul. This temptation is strengthened by statements, both in the Timaeus and elsewhere in the Platonic corpus, that seem to indicate that νοῦς cannot in Plato's view exist apart from soul.Footnote ²⁵ Whether or not one is motivated to resist this temptation, I would suggest, depends chiefly on whether one thinks it necessary to align the Demiurge with the ontological category of unchanging being in order for it (together with the Forms) to stand in the appropriate explanatory relationship to things in the category of what comes-to-be (including the World Soul). If one emphasizes that alignment, as well as the fact that the World Soul's function is to inhabit the world's body and thereby to keep the cosmos and its motions organized, one will presumably think it important to keep Demiurge and World Soul separate.

The Stoics, however, have no use for a realm of Forms, so they have no motivation of that sort to keep the νοῦς of World Soul and the νοῦς that is the Demiurge separate. And they do have a motivation for thinking of the two as substantially identical, in so far as both describe divine providence, i.e. reason's implementation of its determinations of the best way for the cosmos to be. The same goes for the younger cosmic gods, to whom the Demiurge, in a famous speech (41a–d), entrusts the creation and safeguarding of living creatures within the cosmos. Timaeus himself indicates that to understand how the bodies of humans and other animals came to possess their forms, and how their souls are fitted to those bodies, will require no more and no less than a detailed consideration of the younger gods' reasoning (44c): ‘Through what causes (αἰτίαι) did these things come to be, through what plans (προνοίαι) of the gods?’

Timaeus explains the organization of the cosmos, at every level, by appeal to rational planning: that of the Demiurge, and that of the Demiurge's divine instruments (the World Soul, and finally the younger gods). The Stoics were, I have proposed, deeply inspired by this consistent appeal to divine, providential reason as what is explanatory of the disposition of the natural world. Absent Plato's metaphysical reasons to treat the Demiurge as an entity separate from the cosmos – and absent later Platonists' qualms about ascribing to the Demiurge the power to deliberate about the cosmos – the Stoics were free to construe their active principle, present throughout the world, on the model of Plato's Demiurge: as a providential god, acting on its plans for the good ordering of the world.Footnote ²⁶