DIOGENES OF BABYLON ON WHO THE DEITY IS: AËTIUS 1.7.8 MANSFELD–RUNIA RECONSIDERED

Abstract In Aëtius 1.7.8 Mansfeld–Runia, Diogenes, Cleanthes and Oenopides are said to have maintained that the deity is the world-soul. However, the identity of the Diogenes whom the doxographer mentions here has long been a matter of scholarly dispute. In response to attempts to ascribe the doxa to Diogenes of Apollonia, this paper reassesses old arguments and proposes new considerations to argue that a fundamental aspect of Diogenes of Babylon's theology is at stake here.

single philosophers, and for the most part does not match the order of the analogous lists in Cicero's On the Nature of Gods 5 and in Philodemus' On Piety, although in all three lists the beginning and the end, viz. Thales and Epicurus, are the same. Let us compare synoptically the sequence of philosophers provided by these three sources; I highlight in bold the cases in which the name Diogenes appears. Cic This is a necessary precondition for any attempt to resolve an important problem of Aëtius' passage in question, viz. the doxa mentioned above, placed between those of Democritus and Pythagoras, which ascribes the idea that the deity should be identified with the world-soul to Diogenes, Cleanthes and Oenopides alike (Aët. 1.7.8 MR): Διογένης καὶ Κλεάνθης καὶ Οἰνοπίδης τὴν τοῦ κόσμου ψυχήν.
Diogenes and Cleanthes and Oenopides [say that the deity is] the soul of the cosmos. 11 This doxa is transmitted only by Stobaeus (Ecl. 1.1.29b) and is placed between those concerning Democritus' and Pythagoras' theologies: the former identified the deity with the Mind residing in a spherically shaped fire ( §7); the latter considered the Monad as the deity and the Good, and the Undetermined Dyad as a daemon and the Evil ( §9). As for Oenopides (41 A 6 DK), Zeller supposed he was an otherwise unknown Stoic, 12 but this unlikely suggestion has never gained credence. In the Placita, Oenopides appears only twice more, always along with Pythagoras. 13 Independently of the question of the Stoic interpretation of his thought in the Aëtian passage at hand, he should be identified with the homonymous astronomer of Chios (fifth century B.C. chapters of Book 2 of the compendium that deal with the causes of the world's tilt (Τίς ἡ αἰτία τοῦ τὸν κόσμον ἐγκλιθῆναι) 18 and with the world itself, that is, its nature (Περὶ κόσμου), respectively. 19 Lastly, Mansfeld and Runia, in the commentary on their new monumental edition of Aëtius, reiterate that the issue remains unclear, as indicated in their apparatus testimoniorum on page 373, where both possibilities are given. However, they also offer arguments in favour of Diogenes of Apollonia and a 'Stoicizing' reading of his theory of the elements. 20 There are four strong arguments in favour of identifying the Diogenes in Aët. 1.7.8 MR with the Stoic rather than with the Presocratic philosopher. The first three rest on formal aspects of the passage, while the fourth focusses on the philosophical content of the testimonium. 1) It has been observed that the only argument that Diels could have used to rule out the possibility that Diogenes of Babylon is meant in the doxa at issue is that the Stoic would then appear only here in the Placita. 21 But this conclusion is clearly untrue. In Aët. 2.32.9 MR, Diogenes is explicitly indicated as ὁ Στωικός and is said to maintain that Heraclitus' Great Year is to be multiplied by 365 times (SVF III 28). But even if Diogenes of Babylon appeared only here in the compendium, this would not be reason enough to rule out a priori that Aëtius was referring to him in the passage under consideration: his name would not be the only hapax legomenon in the Placita. 22 Among several examples, I find the case of the Stoic philosopher, pupil and successor of Diogenes of Babylon, Antipater of Tarsus, significant. His name appears only in the chapter On Fate (Περὶ εἱμαρμένης) of Book 1 of the compendium, where, immediately after the doxa on Zeno of Citium, he is said to support the theory that God and Fate coincide. 23 2) Moreover, although it is true that in the doxai concerning him Diogenes of Apollonia is rarely cited by Aëtius with his ethnicon, viz. 1.3.10 and 4.3.8 MR, Diogenes of Apollonia is also cited alongside a Stoic only in this passage of the Placita, to the best of my knowledge.
3) The sequence of philosophers in Cicero and Philodemus does not automatically indicate that Aëtius' Diogenes must be the Presocratic philosopher. I have already highlighted above the differences in the content of Cicero's and Philodemus' reports on Diogenes of Apollonia. However, in neither of these reports is Diogenes' theology connected with that of other philosophers, let alone with that of the Stoics. In addition, in the long list from Aëtius, each Presocratic theological doxa is devoted to a single thinker. The only exception is Melissus, who is linked with Zeno of Elea (within the same doxa) in saying that the deity is the One/All, the only entity that is everlasting and unlimited ( §18). 4) The deciding reason, however, for ascribing the Aëtian doxa to the Stoic Diogenes is the philosophical argument. I now develop this point in greater detail.
None of the witnesses in 64 A 8 DK relates Diogenes of Apollonia's view of air qua (physical) principle to the idea of a world-soul. As Laks points out, none of the sources allows us to argue that Diogenes of Apollonia ever upheld the world-soul doctrine or, more generally, the existence of a cosmic intelligence. 24 Neither is this reported in Augustine's account (De ciu. D. 8.2 = 64 A 8 [4] DK), where Diogenes of Apollonia's aer is only said to be provided with a diuina ratio, nor in the other two bits of evidence that are recorded, not in DK, but only in Laks's edition: Clement of Alexandria (Protr. 5.64.1-3 = T 7b Laks) and Minucius Felix (Oct. 19.5 = T 7d Laks). In the doxographical sources specifically devoted to Diogenes of Apollonia's psychology in the Vorsokratiker (64 A 20 DK) as well, no link between the theory of the world-soul and Diogenes of Apollonia appears. In On the Soul (1.2.405a21-5), Aristotle only says that for Diogenes soul is air and, since it is the thinnest of all things, it is also its principle (above all the principle of its motion).
In Book 4 of Aëtius' compendium (4.7.1 MR), the doxa on the indestructibility of the soul is ascribed to Diogenes (of Apollonia) along with Pythagoras, Anaxagoras, Plato, Empedocles and Xenocrates. Note that no Stoic appears here. The Stoics as a general group are discussed instead at 4.7.3 MR. At the end of 64 A 20 DK, Diels adds in parentheses Aët. 4.5.8 MR, where the opinion that the regent part of the soul is placed in the heart's arterial cavity, which is pneumatic (Διογένης ἐν τῇ ἀρτηριακῇ κοιλίᾳ τῆς καρδίας, ἥτις ἐστὶ πνευματική), is ascribed to a Diogenes who is not otherwise specified. Scholars strongly suspect that Aëtius is speaking here not about Diogenes of Apollonia but about Diogenes of Babylon. 25 Moreover, an apparently heterodox opinion in comparison to the official Stoic position-which maintained that the regent part of the soul is found in the entire heart or in the heart-embracing pneuma (Aët. 4.5.7 MR), not in a part of the heart-is ascribed to Diogenes of Babylon. If, as I am inclined to believe, Aët. 4.5.8 MR concerns Diogenes of Babylon's psychology, then its close connection to Galen's witness in SVF III 30-in which the regent part of the soul is said simply to be in the heart-is evident. 26 Finally, among the evidence for Diogenes of Apollonia's psychology in the Vorsokratiker, Diels did not include Aët. 4.3.8 MR (T 5b Laks = 28 D 12 LM), where the essence of the soul is said to be air (ἐξ ἀέρος τὴν ψυχήν). Now, it is clear that Aëtius also speaks in these passages about the soul tout court, not about a world-soul, and that he introduces the doxa under the name of Diogenes, who is unequivocally provided with his ethnicon (Διογένης ὁ Ἀπολλωνιάτης). 27 All the evidence just cited refers only to the physiological aspects of Diogenes of Apollonia's psychology, without ascribing to him the idea of a cosmic soul. Conversely, to prove on a philosophical level that Aët. 1.7.8 MR refers to the Stoic, we need a source that, even indirectly, connects Diogenes' God to psychology, and in particular to a cosmic concept of the soul. This source does exist: Philodemus, in the last section of his treatise On Piety, provides an account of Diogenes of Babylon's theology which is much more detailed than that of the parallel passage in Cicero's On the Nature of Gods. 28 Below I give a synoptic overview of the two texts with a translation.