Stoics: Metaphysics and Physics

A sentence in Book 7 of Diogenes Laertius’s Lives states that, according to the Stoics, the four elements are “unqualified substance, i.e. matter.” Scholars have noted that this appears to conflict with the Stoics’ distinction between principles and elements. Different solutions have been proposed, from dismissing the sentence entirely to emending the text. This note proposes a new interpretation according to which the standard reading of the text can be retained.

Determinism, Freedom, and Moral Responsibility brings together nine substantial essays on determinism, freedom, and moral responsibility in antiquity by Susanne Bobzien. The essays present the main ancient theories on these subjects, ranging historically from Aristotle followed by the Epicureans, the early Stoics, several later Stoics, and up to Alexander of Aphrodisias in the third century CE. -/- The author discusses questions about rational and autonomous human agency and their compatibility with a large range of important philosophical issues, including their compatibility (...) with divine predetermination and other theological questions; with atomism and continuum theory and with the physical sciences more generally; with the determination of character and its development from childhood through nature and nurture; with epistemic features such as ignorance of circumstances; with theories of necessity, possibility and contingency; with external or internal preceding causes and impediments; and with folk theories of fatalism. Room is also given to the questions of how human autonomous agency is related to moral development, to virtue and wisdom, and to blame and praise. -/- Historically unified, philosophically profound, and methodologically rigorous, Bobzien’s essays show that in Classical and Hellenistic philosophy these topics were all debated without reference to freedom to do otherwise or to a free will, and that the latter two notions were fully developed only later. The volume will be of interest both to philosophers and to historians of philosophy, with more than half of the essays accessible to advanced undergraduates. (shrink)

According to the Stoics, ordinary unified bodies—animals, plants, and inanimate natural bodies—each have a single cause of unity and being: pneuma. Pneuma itself has no distinct cause of unity; on the contrary, it acts as a cause of unity and being for itself. In this paper, I show how pneuma is supposed to be able to unify itself and other bodies in virtue of its characteristic tensile motion. Thus, we will see how the Stoics could have hoped to account for (...) corporeal unity by positing another body apparently itself in need of unification. (shrink)

According to the ancient Greek Stoics, the cosmos regularly transitions between periods of conflagration, during which only fire exists, and periods of cosmic order, during which the four elements exist. This paper examines the cosmogonic process by which conflagrations are extinguished and cosmic orders are restored, and it defends three main conclusions. First, I argue that not all the conflagration’s fire is extinguished during the cosmogony, against recent arguments by Ricardo Salles. Second, at least with respect to the cosmogony, it (...) is not necessary to posit the existence of proto-elements. Third, while scholars such as Salles and David Hahm have argued that Cleanthes held a distinct theory of cosmogony from Zeno and Chrysippus, I argue that each of these Stoics endorse the same cosmogonic theory. (shrink)

This volume explores the versatility of the concept of pneuma in philosophical and medical theories in the wake of Aristotle’s physics. It offers fourteen separate studies of how the concept of pneuma was used in a range of physical, physiological, psychological, cosmological and ethical inquiries. The focus is on individual thinkers or traditions and the specific questions they sought to address, including early Peripatetic sources, the Stoics, the major Hellenistic medical traditions, Galen, as well as Proclus in Late Antiquity and (...) John Zacharias Aktouarios in the early 14th century. Building on new scholarly approaches and on recent advancements in our understanding of Graeco-Roman philosophy and medicine, the volume prompts a profound re-evaluation of this fluid and adaptable, but crucially important, substance, in antiquity and beyond. (shrink)

The Pneumatist school of medicine has the distinction of being the only medical school in antiquity named for a belief in a part of a human being. Unlike the Herophileans or the Asclepiadeans, their name does not pick out the founder of the school. Unlike the Dogmatists, Empiricists, or Methodists, their name does not pick out a specific approach to medicine. Instead, the name picks out a belief: the fact that pneuma is of paramount importance, both for explaining health and (...) disease, and for determining treatments for the healthy and sick. In this paper, we re-examine what our sources say about the pneuma of the Pneumatists in order to understand what these physicians thought it was and how it shaped their views on physiology, diagnosis and treatment. (shrink)

In this paper, our intention is to present the main aspects of the understanding of the logos in Philo of Alexandria. Philo’s reception of this notion is especially important because his insights significantly influenced the development of patristic philosophy, and these influences, through the mediation of scholasticism, reached the modern age. Philo has a very important role in creating the Judeo-Christian heritage, and represents an important link for understanding the formation of the basic matrices of this worldview. For the first (...) time, a thorough synthesis of Semitic and Hellenic heritage was performed with him. The use of the term logos in that synthesis proves to be one of the key ones, since it is precisely this term, which has never lost its philosophical significance, partly and thanks to Philo, that is identified with the Son of God of the Christian tradition. (shrink)

This chapter examines the ancient Stoic theory of the physical composition of pneuma, how its composition relates to pneuma’s many causal roles in Stoic philosophy, and to what extent each of the first three leaders of the Stoic school accepted the claim that pneuma pervades the cosmos. I argue that pneuma is a compound of fire and air. Furthermore, many functions of pneuma can be reduced to the functions of these elements. Finally, it is likely that each of the early (...) Stoics posited a pervasive cosmic pneuma. This paper also explores the nature of pneuma’s tensile movement and offers an account of fire and air’s roles in causing its motion. (shrink)

In this work I propose a theory of evolution as a process of unfolding. This theory is based on four logically concatenated principles. The principle of evolutionary order establishes that the more complex cannot be generated from the simpler. The principle of origin establishes that there must be a maximum complexity that originates the others by logical deduction. Finally, the principle of unfolding and the principle of actualization guarantee the development of the evolutionary process from the simplest to the most (...) complex. These logical principles determine the existence of a virtual ideological matrix that contains the sequence of the preformed and folded morphogenetic fields. In this manner, the evolutionary process consists of the sequential unfolding and actualization of these fields, which is motorized by a process of teleologization carried out by the opening consciousness of the forms included in the fields of the ideological matrix. This theory leads to a radical change of perspective regarding the materialist worldview, and places life at the center of the evolutionary process as an activity carried out by a consciousness that seeks to fulfill a purpose by actualizing its own potentialities. (shrink)

This paper traces how the dualism of body and soul, cosmic and human, is bridged in philosophical and religious traditions through appeal to the notion of ‘breath’ (πνεῦμα). It pursues this project by way of a genealogy of pneumatic cosmology and anthropology, covering a wide range of sources, including the Pythagoreans of the fifth century BCE (in particular, Philolaus of Croton); the Stoics of the third and second centuries BCE (especially Posidonius); the Jews writing in Hellenistic Alexandria in the first (...) century BCE (Philo); and the Christians of the first century CE (the gospel writers and Paul). Starting from the early Pythagoreans, ‘breath’ and ‘breathing’ function to draw analogies between cosmogony and anthropogony – a notion ultimately rejected by Plato in the Timaeus and Aristotle in his cosmological works, but taken up by the Posidonius (perhaps following the early Stoa) and expanded into a rich and challenging corporeal metaphysics. Similarly, the Post-Hellenistic philosopher and biblical exegete Philo of Alexandria, who was deeply influenced by both Platonist and Stoic physics, approaches the cosmogony and anthropogony described in Genesis (1:1–3 and 1:7) through Platonist-Stoic philosophy, in his attempt to provide a philosophically rigorous explanation for why Moses employed certain terms or phrases when writing his book of creation. Finally, the chapter sees a determined shift in the direction of rejecting pneumatic cosmology for a revised pneumatic anthropogony in the writings of the New Testament: by appeal to the ‘Holy Spirit’ or ‘Holy Breath’ (πνεῦμα ἅγιον), early Christians effectively adapted the Stoic metaphysics of ‘breath’, with its notions of divine intelligence and bonding, to the prophetic and ecclesiastical project of building a Christian community conceived of as the ‘body of Christ’. Hence, the spiritual cosmogony of the Pythagoreans, Stoics, and Philo is effectively subordinated to the spiritual anthropogony that facilitates the construction of the Christian kosmopolis, only fully realised in the form of New Jerusalem, the ‘bride’ which, in tandem with the Holy Spirit, calls to the anointed. At the end of the Christian worldview, the kosmos of Greek philosophy is supplanted by the pneumatic kosmopolis. (shrink)

The purpose of this paper is to identify the upholders of the thesis reported by Plutarch, De Stoicorum repugnantiis 23, aimed to reject Stoic determinism. A brief introduction will be devoted to the relationship between this text and the more general context of the Stoic philosophy. Then, I will take into account the objection against Stoic determinism raised by some anonymous philosophers: according to it, causal determinism would be inconsistent with the choice among indistinguishables. Chrysippus replied that if that choice (...) were not determined, it would occur without causes; and this would be absurd. Then I will summarize the most likely hypotheses about the identification of Chrysippus’ opponents, and I will opt for Academics. Finally, I will try to conjecture the link between Plutarch’s passage and the debate among Stoics and Academics about indistinguishables, as we know it from other sources. (shrink)

Can the Stoic conception of what is within our power be adapted to fit our scientifically informed view of nature in general and of human nature in particular? This paper argues that it can, but not without a revision of the Stoic’s classical dichotomy of power principle, namely that some things are up to us, while others are beyond our control. Given the extent to which the Stoic way of life flows from a certain conception of what is real, a (...) revision of the latter is bound to affect the former. The central argument is that for the modern Stoic, follow the facts means that nothing is entirely under our control just as nothing is entirely beyond it. Rather, things are more or less within my power, depending on the range of possibilities that living in accordance with a constantly evolving conception of nature affords. (shrink)

This paper rehabilitates the Stoic conception of blending from the ground up, by freeing the Stoic conception of body from three interpretive presuppositions. First, the twin hylomorphic presuppositions that where there is body there is matter, and that where there is reason or quality there is an incorporeal. Then, the atomistic presupposition that body is absolutely full and rigid, and the attendant notion that resistance (antitupia) must be ricochet. I argue that once we clear away these presuppositions about body, the (...) foundations of Stoic corporealism fall into place. Body is fundamental (not hylomorphic). The two fundamental principles (archai) are bodies: divine active reason (logos) and passive matter (hulē); and these two bodies are two, not matter and form all over again, nor actual and potential, but agent and patient. The independence of the two archai is no threat to the unity of the cosmos, however, because the Stoic theory of body allows for the complete coextension of the archai. The hylomorphic thinker rightly asks, what relation could be tighter than that of the wax and its shape? The Stoic replies: a causal relation, the interaction of agent and patient completely coextended in a through and through blend. (shrink)

_ Source: _Volume 63, Issue 1, pp 87 - 116 In Stoic physics, blending is the relation between active pneuma and passive matter; natural bodies from rocks and logs to plants, animals and the cosmos itself are blends of pneuma and matter. Blending structures the Stoic cosmos. I develop a new interpretation of the Stoic theory of blending, based on passages from Hierocles. The theory of blending, I argue, has been misunderstood. Hierocles allows us to see in detail how the (...) theory is supposed to work and how it fits into Stoic physics. (shrink)

Sources for Stoicism present conflicting accounts of the Stoic principles. Some suggest that the principles are inseparable from each other. Others suggest that they are separable. To resolve this apparent interpretive dilemma, I distinguish between the functions of the principles and the bodies that realize those functions. Although the principles cannot separate when realizing their roles, the Stoic theory of blending entails that the bodies that realize those roles are physically separable. I present a strategy for further work on the (...) principles in light of this interpretation. (shrink)

In this paper, I clarify some central aspects of Stoic thought concerning identity, identification, and so-called peculiar qualities (qualities which were seemingly meant to ground an individual’s identity and enable identification). I offer a precise account of Stoic theses concerning the identity and discernibility of individuals and carefully examine the evidence concerning the function and nature of peculiar qualities. I argue that the leading proposal concerning the nature of peculiar qualities, put forward by Eric Lewis, faces a number of objections, (...) and offer two constructive suggestions which turn upon reconsidering the nature and function(s) of peculiar qualities. Finally, I examine a simple but potent Academic argument against the view that identification requires detecting some attribute(s) unique to the relevant individual. Such an argument is, I argue, largely successful and may have encouraged later Stoics not to think that peculiar qualities enable identification. (shrink)

One of Leibniz’s more unusual philosophical projects is his presentation (in a series of unpublished drafts) of an argument for the conclusion that a time will necessarily come when “nothing would happen that had not happened before." Leibniz’s presentations of the argument for such a cyclical cosmology are all too brief, and his discussion of its implications is obscure. Moreover, the conclusion itself seems to be at odds with the main thrust of Leibniz’s own metaphysics. Despite this, we can discern (...) a serious and important point to Leibniz’s consideration of the doctrine, namely in what it suggests about the proper boundary between metaphysics and theology, on the one hand, and ordinary history (whether human or natural), on the other. And we can get a better sense of Leibniz purpose in the essays by considering them in the context of Leibniz's response to Thomas Burnet's "Telluris theoria sacra" (1681-89). Leibniz praises Burnet's history of earth for presenting a harmony between the principles of nature and grace, a harmony absent in the cosmogonies of Descartes and the Newtonians. But Leibniz also complains that Burnet misconceives the boundary between natural explanation and reflections on divine wisdom. And Leibniz's essays on cyclical cosmology suggest the alternative to Burnet's account: a natural history of the earth and its inhabitants should be radically autonomous from, even if ultimately harmonious with, theological principles. (shrink)

Chrysippus often talks as if there is a third option when we might expect that two options in response to a question are exhaustive. Things are true, false or neither; equal, unequal, or neither; the same, different, or neither.. and so on. There seems to be a general pattern here that calls for a general explanation. This paper offers a general explanation of this pattern, preserving Stoic commitments to excluded middle and bivalence, arguing that Chrysippus employs this trichotomy move when (...) he wishes to argue that apparent contradictories are only contraries, and wishes to endorse a third option. This general explanation of the pattern of trichotomies sheds light on a number of interpretive puzzles, including on Chrysippus's response to the paradox of the cone. The purpose of these trichotomies is also discussed, and it is suggested that they originate from the dialectical context in which philosophical problems were posed. (shrink)

Void is at the heart of Stoic metaphysics. As the incorporeal par excellence, being defined purely in terms of lacking body, it brings into sharp focus the Stoic commitment to non-existent Somethings. This article argues that Stoic void, far from rendering the Stoic system incoherent or merely ad hoc, in fact reflects a principled and coherent physicalism that sets the Stoics apart from their materialist predecessors and atomist neighbors.

Margaret Cavendish was an English natural philosopher. Influenced by Hobbes and by ancient Stoicism, she held that the created, natural world is purely material; there are no incorporeal substances that causally affect the world in the course of nature. However, she parts company with Hobbes and sides with the Stoics in rejecting a participate theory of matter. Instead, she holds that matter is a continuum. She rejects the mechanical philosophy's account of the essence of matter as simply extension. For Cavendish, (...) matter is also essentially living, sensing, and rational. She also rejects the mechanical philosophy's explanation of change solely in terms of transference of motion. Her own explanation of change relies upon a notion of "occasional cause." This paper argues that Cavendish's occasional causes are not to be confused with those of Malebranche; hers have some efficient causal powers. It traces the concept of an occasional cause from the ancient Stoics, through Galen, to Renaissance natural philosophers such as J. B. van Helmont, and ultimately to Cavendish and to Descartes. Thus, the aim of the paper is to explicate Cavendish's non-mechanical model of natural change and to show how the key concept in this model, that of "occasional cause," has a long philosophical pedigree. L'anglaise Margaret Cavendish pratique la philosophic naturelle. Sous l'influence de Hobbes et du stoïcisme ancien, elle a soutenu que le monde naturel créé est purement matériel ; dans le cours de la nature, il n'y a pas de substances incorporelles qui affectent causalement le monde. Elle se sépare néanmoins de Hobbes et rejoint les Stoïciens dans son rejet d'une théorie de la matière particulaire. Elle considère au contraire que la matière est un continuum. Elle rejette l'explication de l'essence de la matière comme simple extension, fournie par la philosophic mécaniste. Pour Cavendish, la matière est de plus essentiellement vivante, sentante et rationnelle. Elle rejette aussi l'explication mécaniste du changement en simples termes de transmission de mouvement. Sa propre explication du changement s'appuie sur la notion de cause occasionnelle. Cet article defend l'idée que les causes occasionnelles de Cavendish ne doivent pas être confondues avec celles de Malebranche ; les siennes ont des pouvoirs causaux efficients. Il permet done de suivre l'histoire du concept de cause occasionnelle des anciens Stoïciens, en passant ensuite par Galien jusqu'aux Philosophes de la nature de la Renaissance, comme J. B. van Helmont, et finalement jusqu'à Cavendish et Descartes. Le but de cet article est ainsi de rendre explicite le modèle que Cavendish donne du changement naturel et de montrer comment le concept clé de ce modèle, celui de cause occasionnelle, est le produit d'une longue filiation philosophique. (shrink)

Reconstructs the original Greek version of the confatalia-argument that Cicero attributes to Chrysippus in De fato and misrepresent in crucial ways. Compares this argument with Seneca's discussion of determinism in the Naturales quaestiones. Clarifies that Seneca makes a different distinction from that attested in Cicero's De fato. Argues that problems with interpreting both accounts derive from disregarding terminological distinctions harder to spot in the Latin versions and, related to this, insufficient attention to the ontological distinction between bodies (such as Fate) (...) and predicates (e.g. "what is fated"), which unfortunately does not square well with the modern ontological category "event." Contains some corrections to the author's earlier discussion of the topic in Seneca und die Stoa: Der Platz des Menschen in der Welt, De Gruyter 2006, ch. 3.3.4. (shrink)

The later Stoics, especially – and most notably – Posidonius of Apamea, allegedly the greatest polymath of his age and the last in a celebrated line of great philosophers of the ancient world, gradually developed the belief that all parts of the universe, either ensouled or not, were actually interconnected due to the omnipresent, corporeal, primordial kosmikon pyr which, according to Stoicism, pervades each being as the honey pervades the honeycomb. As for reasonable beings, in particular, kosmikon pyr takes the (...) form of logos. Due to that power, Posidonius believes, the phases of moon, for instance, can affect the succession of tides and ebb–tides; on the same grounds, the signs can have major effect on the course of events and, therefore, allow for divination. That kind of interconnectedness, apart from justifying the interdependentness of all beings to each other, testifies for an utter kinship between them, for sympatheia. In this short paper I intent to show that Posidonius’s approach has been promptly adopted and utilized by modern holistic theories concerning Environmental Ethics, especially by Arne Naess’s Deep Ecology and Ecosophy T, in the context of which notions such as kinship, interconnectedness, interdependentness and identification of all beings are key parameters for the articulation of their argumentation. I also intent to outline some essential – in my opinion – differences in the way Posidonius and Naess make use of the notion of interconnectedness, together with some inconsistencies which can be potentially fatal, at least as far as a system of ethics is concerned. This is because notions such as cosmic sympathy may possibly establish an interesting, even charming and influential cosmology or metaphysics, but when it comes to ethics, in my opinion, they can only provide shaky grounds for establishing a firm one, since they allow for deterministic views, which more or less leave no room for personal responsibility, to wit for personal praise or blame. (shrink)

Záměr zkoumat metafyziku stoické filosofické školy naráží na řadu problémů. Předně se metafyzikou zabývali zejména nejstarší stoičtí filosofové, především Zénón, Chrýsippos a Kleanthés, ovšem bohužel právě od nich se plně nedochoval žádný spis a tak o jejich filosofických postojích získáváme informace z druhotných zdrojů, jejichž autoři měli často ke stoické filosofii odmítavý postoj. Zároveň se názory těchto myslitelů v určitých bodech rozcházely a stoická filosofie sama procházela vývojem a proměnami, které zprostředkovány jen druhotnými zdroji působí značné interpretační potíže. Přes tyto (...) obtíže se v tomto textu pokoušíme podat přehled základní struktury stoické metafyziky, tak jak se v tomto nejstarším období zformovala, přičemž poukazujeme na některé problémové či sporné otázky. Východiskem je pro naši analýzu pojem tělesa, od něhož docházíme k rekonstrukci třístupňové stoické metafyziky a nejuniverzálnější kategorie „něco“. Následně se věnujeme činnému a trpnému principu tělesnosti a od nich se odvíjejícího metafyzického systému. (shrink)

L’article analyse les témoignages stoïciens qui définissent la divinité comme «intellect» et comme «âme du monde», et qui permettent de déterminer les contenus de la pensée divine comme logoi, c’est-à-dire certains «discours» ou «raisonnements». En premier lieu, on examine les mots νοερόν, et νοητόν pour établir à quelles réalités les Stoïciens confèrent les caractères d’intelligence et d’intelligibilité et comment ils décrivent la pensée scientifique à laquelle ils comparent la pensée divine. En second lieu, on examine la théorie des raisons séminales (...) et ses relations historiques avec le problème des objets de la pensée divine. Enfin, on tente de montrer que les Stoïciens, tout en suivant la théologie démiurgique du Timée, unifient ce que Platon a tenu bien séparé : le Démiurge lui-même, l’âme du monde, le «vivant intelligible». (shrink)

The purpose of the present article is to show that there is a clear line of continuity between the early Stoics’ and Cornutus’ works, as all of them assumed that the ancient mythmakers had transformed their original cosmological conceptions into anthropomorphic deities. Hence, the Stoics from Zeno to Cornutus believed that the names of the gods reflected the mode of perceiving the world that was characteristic of the people who named the gods in this way. Accordingly, the major thesis advanced (...) in the paper proposes that the Stoics conducted their etymological analyses so as to gather ethnographical information about the origin and development of the existing religion. When doing so, they treated the conventional mythological narratives as sources of information about the early conceptions of the cosmos. Th us, the Stoics from Zeno to Cornutus employed etymology as a certain research strategy: they analyzed the names of traditional deities so as to extract the physical and moral beliefs that constituted the ancients’ world picture. Treated as ethnologists, the Stoics seem to equate piety with retrieving philosophical truths obscured under the guise of primitive mythical formulations. Furthermore, when unravelling the original worldview inadvertently transmitted by the poets in their poems, the Stoics reconstruct the history of religion and contribute to the development of ancient anthropology. (shrink)

This is a study of the psychological ideas of Galen (AD 129-c.210, the most important medical writer in antiquity) and Stoicism (a major philosophical theory in ...

How does God think? How, ideally, does a human mind function? Must a gap remain between these two paradigms of rationality? Such questions exercised the greatest ancient philosophers, including those featured in this book: Socrates, Plato, Aristotle, the Stoics and Plotinus. This volume encompasses a series of studies by leading scholars, revisiting key moments of ancient philosophy and highlighting the theme of human and divine rationality in both moral and cognitive psychology. It is a tribute to Professor A. A. Long, (...) and reflects multiple themes of his own work. (shrink)

Book synopsis: Plato is perhaps the most readable of all philosophers. Recent scholarship on Plato has focused attention on the dramatic and literary form through which Plato presents his philosophy, an integral part of that philosophy. The papers in this volume for the first time consider Aristotle and the Stoics as readers of Plato. That these successors were influenced by the thought of Plato is a commonplace: the ‘whole of western philosophy is a series of footnotes to Plato’. Arising from (...) Institute of Classical Studies Research Seminars in 2004-5 and 2005-6, the papers in this volume rather consider whether and how the philosophical concerns of these later thinkers were served were served by close reading of Plato, through inter-textual engagement with specific passages of Plato’s works. (shrink)

A survey of Stoic views on religion, with an emphasis on their proofs of the existence and nature of Zeus.

Scholars have long recognised the interest of the Stoics' thought on geometrical limits, both as a specific topic in their physics and within the context of the school's ontological taxonomy. Unfortunately, insufficient textual evidence remains for us to reconstruct their discussion fully. The sources we do have on Stoic geometrical themes are highly polemical, tending to reveal a disagreement as to whether limit is to be understood as a mere concept, as a body or as an incorporeal. In my view, (...) this disagreement held among the historical Stoics, rather than simply reflecting a doxographical divergence in transmission. This apparently Stoic disagreement has generated extensive debate, in which there is still no consensus as to a standard Stoic doctrine of limit. The evidence is thin, and little of it refers in detail to specific texts, especially from the school's founders. But in its overall features the evidence suggests that Posidonius and Cleomedes differed from their Stoic precursors on this topic. There are also grounds for believing that some degree of disagreement obtained between the early Stoics over the metaphysical status of shape. Assuming the Stoics did so disagree, the principal question in the scholarship on Stoic ontology is whether there were actually positions that might be called "standard" within Stoicism on the topic of limit. In attempting to answer this question, my discussion initially sets out to illuminate certain features of early Stoic thinking about limit, and then takes stock of the views offered by late Stoics, notably Posidonius and Cleomedes. Attention to Stoic arguments suggests that the school's founders developed two accounts of shape: on the one hand, as a thought-construct, and, on the other, as a body. In an attempt to resolve the crux bequeathed to them, the school's successors suggested that limits are incorporeal. While the authorship of this last notion cannot be securely identified on account of the absence of direct evidence, it may be traced back to Posidonius, and it went on to have subsequent influence on Stoic thinking, namely in Cleomedes' astronomy. (shrink)