Aristarchus of Samos on Thales' Theory of Eclipses

LEBEDEV,A V. | AVE mov or Aristarchus of Samos on Thales’ Theory of Eclipses Andrei V. Lebedev The remains of the second-century commentary on Odyssey XX published by M.W. Haslam have brought to light a new astronomical fragment of Heraclitus! and an important evidence on Thales’ theory of eclipses which should be added to any future edition of the relevant testimonia: P Oxy 3710 col 11 36-43; vol LI (1986) 97 ötı év vouunvia ai E«Aciers SnAioî "Apiotapyoc 6 Eápuos ypápov: En te 6 uëv Gars [Ot]? ËkxAgire TOV mov ceMmvnc Eninpoodev abrw yevouévne onpeovpel vos tobro] and” Tis iuépas Ev i) moretrar tiv Ékkkeupiv, fiv of pèv tpiaxáda karodaw, ol Se vouunviav. "Hpaxksırog ktA. Adelevi; num ¿1? bsupplevi; onuerovnié [vns c.6] ... ed. That the eclipses occur at noumenia is made clear by Aristarchus of Samos who writes: “Thales said that the eclipse of the sun occurs when it is screened by the moon; he inferred this [theory] from the day in which the sun is [regularly] eclipsed. This day is called ‘the thirtieth’ by some, ‘noumenia’ by others.” The supplement of the editor is unlikely, first, because it results in syntactical hardness; second, because onuevbuar in philosophical and scientific literature usually has medial (not passive) force and is Lesepev Andrei V., Aristarchus of Samos on Thales’ theory of eclipses : Apeiron XXIII 1990 77-85, | On the quotation from Aristarchus in P. Oxy. 3710. | The ascription of the &xınpdoßeang theory of eclipses to Thales was not first made in the Ist cent. B.C, by « Posidonian » doxography : Aristarchus of Samos knew it and his source was the Pre-Peripatetic tradition of the Sth cent, B.C. 1 M.L. West, ‘A new fragment of Heraclitus’, Zeitschrift fiir Papyrologic und Epigraphik 67 (1987) 16 (243 me

Theory of Eclipses The remains of the second-century commentary on Odyssey XX published by M.W. Haslam have brought to light a new astronomical fragment of Heraclitus! and an important evidence on Thales’ theory of eclipses which should be added to any future edition of the relevant testimonia: P Oxy 3710 col II 36-43; vol LIT (1986) 97 511 Ev vovunvia ai ÉKAEÏYELS Snroti ’Apiotapyos 6 Zanıog ypápov: Epn te 6 pèv Oaañc {dt}? ExxAginev TOV HALOV GEATVNG ExinpoobEV abTW yevouévne ONUELOUUE[ vos TODTO] ano? tic huépas év À noveitar Tv ÉKKAELWIV, fiv oi pèv tpiakáda kakodoiv, oi Se vovunviav. “HpaKAeitoc KTA. adelevi; num ¿1? Psupplevi; onueiovué [vnc c.6] ... ed. That the eclipses occur at noumenia is made clear by Aristarchus of Samos who writes: “Thales said that the eclipse of the sun occurs when it is screened by the moon; he inferred this [theory] from the day in which the sun is [regularly] eclipsed. This day is called ‘the thirtieth’ by some, ‘noumenia’ by others.” The supplement of the editor is unlikely, first, because it results in syntactical hardness; second, because onuetoôuat in philosophical and scientific literature usually has medial (not passive) force and is 1 M.L. West, ‘A new fragment of Heraclitus’, Zeitschrift fiir Papyrologic und Epigraphik 67 (1987) 16 APEIRONa journal for ancient philosophy and science

synonymous with tekuaipopai Ex or G6 tvoc.? The meaning of Aristarchus’ evidence is clear: (a) Thales had observed that the eclipses of the sun usually occur at noumenia; (b) from this observation he inferred that on this day the moon is in conjunction with the sun and, consequently, is the cause of its occultation.? The &nınpöoßeoig theory of eclipses is now attested for Thales two centuries earlier: hitherto our earliest authorities have been Cicero and Placita Philosophorum (ca. mid-first century BC).4 The author of the Commentary on Odyssey, as it seems, quotes Aristarchus not directly, but via Diodorus of Alexandria, who was (as I believe) one of the main sources of Placita in astronomy.5 It is natural to conclude that the testimony of Placita also 2 See the instances cited in LSJ, s v onueión II 2 (‘infer as from sign’), and add Sextus Empiricus Adv Math VII 365; VIII 270, etc. onpetobpai Ex is more common, but cf. Cleomedes de motu circ 140 12 Ziegler onueioDtai dè Kai and OKIMV un eivor NOSiaiov tòv fMov. Cf. a similar report on Thales’ empirical inference: DL I 24 texpaipopevov Ex Tic AiBov. A less probable supplement would be onuaoduelvos toms] and; cf. similar reconstructions of Thales’ tekunpia in Aristotle Metaph 983b22 (=11 A 12 DK) Aaßwv iowc ... Ex tod KT. a22: 66ev tows... The possibility of the reading -uevoc did not escape the notice of Haslam: see his note on p.107; other proposals made there (tf xpùye and ti ovvddq@) are certainly wrong. 3 &nuimpdabeaic (=Eninpoodev Yiveodaı) is Aristarchus’ terminus technicus for ‘occultation’: see nepi peye8@v 8; 382 5 Heath éninpdobeaw tic oeANvnG ExdAcinet (sc. è floc). The variant Enınpöoßnaig first occurs in Aristotle, de Caelo 297b29; 293b22, cf. fr.204 Rose = 58 B 37 DK. It is worth noting that in the last two instances Aristotle relates Pythagorean theories, cf. W. Burkert, Lore and Science in Ancient Pythagoreanism (Cambridge, MA 1972), 338-44. Of the two synonymous (and often interchangeable) terms, &nınpöoßeoıg (Exit pooGEw) and àvtigpatic (avrıppätıo), the first seems to be more abstract and ‘scientific’ (also used in geometry: Aristotle, Top 148b27), the second more concrete and informal. so one might guess that the first is of Academic (Pythagorean) and the second of Anaxagorean (Ionic) origin; but there can be no certainty: see indices to DK and Dox Gr, qq.vv. 4 Placita (Plutarch, Stobaeus) II 24 1 = A 17a DK. The source of the corresponding passages in Achilles Isagoge, 46 32 sq. and 50 2 sq. Maass is not ‘Poseidonios’ (contra DK I 78, note 23), but Eudorus-Diodorus. Cf. also the related placita 11 28 5 = 11 A 17b (the moon illuminated by the sun) and II 29 6 (Stobaeus only): Thales, Anaxagoras, Plato, Stoics, pa®npatiKkoi on the eclipses and ‘monthly occultations’ of the moon (not in DK). 5 Diodorus (quoted by the Commentator in col II 47) is certainly the source of the Heraclitus quotation which cannot be separated from the preceding piece of Thales doxography (cf. note 21). It will be demonstrated elsewhere that the

derives from Aristarchus via Diodorus. This tradition certainly does not derive from Eudemus who ascribed the discovery to Anaximenes (?).® Following the lines of Dielsian Quellenforschung one would inevitably conclude that we are dealing with an Alexandrian invention, i.e., that (b) is a conjectural inference from the story of prediction of the eclipse of 585 BC, which has been seriously discredited by O. Neugebauer’s criticism.” The knowledge of the true cause of eclipses is commonly denied to Thales on the ground that it was still ignored by Anaximander and Anaximenes.® I do not intend to disprove the communis opinio, nor main doxographical source of Achilles’ Isagoge is not ‘Plutarchus’ (contra Diels), but Eudorus who relies on Diodorus (30 20 Maass). I suspect also that the lemma pabnpatixoi (i.e., ‘astronomers’) in Placita philosophorum stands for Diodorus of Alexandria who represents the Aristarchean tradition. Thus the combination of Thales and pa@nuarixoi in Placit II 29 6 may be taken as a source reference to Diodorus who reports Aristarchus’ evidence on Thales’ astronomy. 6 Eudemus fr.145 Wehrli ap.Theo Smyrn., 198 14 Hiller = 13 A 16 + 11 A 17 DK. It has long been seen that ’Avat wévns is probably a misquotation of °Avatay6pac: P. Tannery, Pour !’ histoire de la science hellène (Paris 1887), p.153 of the Russian translation (St. Petersbourg 1902); D. Lanza, Anassagora (Firenze 1966), 134. The vague expression eüpe ... HAiov ¿xx2emyw (of Thales) certainly does not imply ‘the discovery of the true cause’, but refers to the ‘prediction’ story. The meaning of Eudemus’ report is misrepresented by G.S. Kirk (in Kirk-Raven-Schofield, The Presocratic Philosophers [Cambridge 19857], 82) for he vn Ex tod ignores the context: "Ava&ınevng dé [sc. edpe rpotoc] dti y cerñ Adiov Eyer tò pús KtA. Thus Kirk’s imputation to Eudemus (‘... was guilty of drawing a wrong conclusion’, etc.) is absolutely unfounded: Eudemus can hardly be guilty of ignoring the fact that it is impossible to discover the cause of eclipses without knowing that the moon is a ‘dark body’ illuminated by the sun. 7 O. Neugebauer, The Exact Sciences in Antiquity (Oxford 1951), 136, 114 (p.144 of the Russian translation [Moscow 1968]) denies the very notion of saros as astronomical cycle. The saros theory is restated by L. Blanche, ‘L’éclipse de Thalès et ses problemes”, Revue Philosophique 158 (1968) 153-99. 8 So already Tannery, 62 (of the Russian translation); J. Burnet, Early Greek Philosophy (London 1920), 41; W.K.C. Guthrie, A History of Greek Philosophy, vol I (Cambridge 1967), 48; Kirk-Raven-Schofield, ibid.; Diels-Kranz I 79 19 note. Another argument is the supposed inconsistency of Thales’ cosmology with the ¿mmpóodeo1s theory which, as we are told, requires a spherical earth and geocentric system. This argument is inconclusive: Anaximenes, €.g., thought that the stars revolved not úxo yfv, but nepi yîiv (13 A 7, $ 6; A 14) and nevertheless held a kind of &nınpöoßdeaig theory: the sun is screened by

do I think that the new evidence is so strong and indisputable as to overthrow it. Yet the authority of Aristarchus allows us to depart for a moment from the negative dogma and to consider ex hypothesi the possibility of a more positive evaluation of the tradition. Our knowledge of sixth-century astronomy is too defective to allow dogmatic conclusions; the history of Greek science is by no means throughout progressive;? and there are cases when the Alexandrian tradition about early gvoikoi, though independent of the Peripatos, is nevertheless reliable.!° Suppose, for example, that Aristarchus got his notice from an early writer (most probably Democritus)! overlooked the earth, the moon by ‘invisible bodies’. No ancient source says that Thales regarded the earth as a flat disc (though this is repeated again and again in modern handbooks). Thales may have conceived the earth as a hill or a mountain floating on the boudless Ocean: the heavenly bodies would revolve nepi yfiv as in Anaximenes’ cosmology without Aoetpa@v "Qxeavoio (contra M.L. West, Early Greek Philosophy and the Onent [Oxford 1971], 211). Thus it is precarious to credit the father of the rational science with the curious notion of ‘semi-orbits’ (?) as G.S. Kirk does, KRS, 83. 9 E.g., Anaximander’s great discovery of the Southern Celestial Hemisphere and antipodes was rejected by Anaximenes who revived in a rationalized form Hesiod’s ‘windy Tartarus’ (cf. B. Gladigow, ‘Pneumatik und Kosmologie’, Philologus, TI (1967) 1-20. 10 Eratosthenes is the only source on Anaximander as geographer: 12 A 6 DK; W.A. Heidel, ‘Anaximander’s Book the Earliest Known Geographical Treatise, Proceedings of the American Academy 1921, Nr.7 11 I believe that the meaning of Hippias as a Pre-Aristotelian source on Thales’ doctrines has been somewhat exaggerated (for a recent discussion of the Hippias question see J. Mansfeld, Mnemosyne 38 (1985) 109-29). In particular, though Hippias was interested both in Thales and astronomy, there is no positive evidence that he ever said something about Thales’ astronomy. DL I 23 cites as early authorities on Thales’ astronomy Xenophanes (= 21 B 19 DK), Heraclitus (= B 38 DK = 63 b Marcovich), Democritus (= B 115a DK = 156 Luria). Democritus must have been most informative of all; he was also interested in Thales’ biography and reported details on Thales’ Phoenician ancestry (DL I 22), appreciated by Hellenistic diadochai writers as a first-hand Ionian tradition. Since Democritus wrote no biographical works, this last notice probably derives from a ‘scientific biography’ of Thales sketched in one of Democritus’ astronomical treatises. The list of Pre-Eudoxan astronomers in Vitruvius IX 6 3 (Thales, Anaxagoras, Pythagoras, Xenophanes), ending with Democritus himself, is probably quoted from Democritus’ "Aotpovouin: see 68 B 14, 1 DK

by Eudemus. Another reputed eòpetic of the cause of eclipses, Anaxagoras, was accused by Democritus of ‘having stolen his theories about the sun and the moon’ from the ancients, i.e., from the Milesians. !2 Both the true nature of poticuoi Tg oeAnvng and (I believe) the true cause of solar eclipses were known to Parmenides ca. 500-490 BC.13 Parmenides probably got his knowledge from the Pythagorean tradition, and so another line of convergence leads us from Pythagoras to the Milesians. The Orphic Derveni Theogony (about the same time or = 424 Luria. If so, Democritus certainly regarded Thales as the father of scientific astronomy and physics long before Aristotle. Though Theophrastus wrote ‘On Democritus’ astronomy’ (DL V 43), it is far from certain whether the Peripatetics possessed the whole of ‘Corpus Democriteum’. But the Alexandrians certainly possessed it in its integrity and studied Democritus’ language and style (68 A 32). It is a priori improbable that a man like Aristarchus of Samos, an Ionian in blood and spirit, never unrolled Democritus’ nadnnartıka (tetral VII-IX). 12 DL IX 43 35 = Favorinus fr.44 Mensching = Anaxagoras A 5 DK = Democritus fr 159 Luria. Diels’ identification of àpyaior (DK II 50 n.2) with ‘Leucippus’, the supposed teacher and older contemporary of Democritus, is surprising. It has been rightly refuted by Mensching, Favorin von Arelate I (Berlin 1963), 135; Lanza, Anassagora, 16-17; Luria, Democritea (Leningrad 1970), 459. Anaximenes with his theory of ‘invisible bodies’ (A 7, § 5; A 14, cf. Anaxagoras A 42, § 9; A 77) is probably meant. But the expression ai 50Ga1 at te nepi NAlov Kai oeANvng is too general and there is no evidence that Anaxagoras (like Anaximenes) applied the theory to the eclipses of the sun. The core of Anaxagoras’ ‘opinions about the sun and the moon’ is that they are ‘stones’. Since neither Anaximander nor Anaximenes held such a doctrine, it was natural to conclude that by äpxaioı Democritus meant Thales. Democritus himself accepted the theory of stars as ‘ignited stones’ (A 84 87 DK = 393, 396 Luria). Since he was offended by Anaxagoras (DL IX 35, cf.II 14 where Anuokpitw) his aim was to diminish the originality of Anaxagoras and to reject the potential charge of plagiarism against himself by pointing out to Thales as the true author. There is an interesting echo of the Democritus- Anaxagoras scandal in Plato’s Cratylus 409a9 (noticed by J. Mansfeld, Mnemosyne (1980), 90, n.333) Eoıxe ônAODVTL NaAaLOTEpOV KTÀ. (cf.59 A 76 DK): Anaxagoras’ theory of the moon illuminated by the sun turns out to be pre-historical, expressed already by övonatoߣrng in the name oeAnvn! Note the hyperbolic and humorous charge of plagiarism which sounds as a parody. The Cratylus passage is decisive for the determination of àpyaiar 66Ga1 ‘stolen’ by Anaxagoras. 13 Parmenides B 14; B 10 3 py’ àiônAa of the sun = eclipses; cf.A 42 (demonstrabitur). I regard Parmenides’ meeting with Socrates in Plato’s Parmenides as fiction, and follow the chronology of Appollodorus (recte Jacoby).

somewhat earlier) alludes to the spherical moon conceived as ‘another earth’ which presupposes that it shines by ‘reflected light’. It is worth noting that the ‘Placita’ consistently ascribe to Thales the doctrine of the earthen nature of the moon and the stars.f It can be explained away as a doxographical reconstruction from the éximpdo@Eoic theory (which presupposes a non-transparent moon), i.e., from another reconstruction(!). But the new evidence allows another explanation: these astrophysical placita of Thales, interconnected with those on portiouoi and eclipses, also derive via Eudorus-Diodorus from Aristarchus who got them from an ancient source unknown to or unnoticed by the Peripatetics. The sceptic may object that even if Aristarchus was the source, he simply inferred the whole complex from Democritus’ accusing Anaxagoras of plagiarism by atributing the äpxaioı 56€a1 to Thales as ‘the true author’ of Anaxagoras’ doctrines.!6 But the traditionalist will reply that even in this case (which is far from certain) Aristarchus’ inference may have been partly correct.?” 14 col XXI = 1141-2 West (Orphic Poems [Oxford 1983], 115) who plausibly combines these lines with Orpheus fr 91 Kern. 15 Placit II 13 1 (Gotpa yewdn); 11,20,9 (yeoedt tov Mov; II 25 8 (yeddq thv ceAnvnv). It is not easy to see why Kranz (11 A 17a DK) includes the first two placita and omits the third: they must stand or fall together. 16 It is remarkable that Anaxagoras’ theory of eclipses is derived directly from Thales in Cicero, Rep I 16 25; In Placit li 29 5 Thales and Anaxagoras are the only Pre-Platonic philosophers combined with pa@npatiKoi (i.e., the Diodorus and Aristarchean tradition, cf. note 4 above); Placit II 28 5 OaAñc rpótos Epn Ürd TOD HAiov Pwrileodau ... "Avacaydpac ôuoiwc. Cf. also the combination Thales, Anaxagoras... Democritus in Vitruvius (note 11 above). 17 The case becomes more complicated if Democritus went so far as to derive Anaxagoras’ theory from pre-historical sages (cf. the Cratylus passage, note 12 above) whose views can be reconstructed by means of etymology and allegorical interpretations of myths: 68 B 25 = 397a, 821 Luria proves that Democritus practiced such interpretations. The Anaxagoreans themselves were leading proponents of such methods in the last third of the fifth century: Metrodorus of Lampsacus, the Derveni Anonymus, Euripides, who in particular interpreted Tantalos’ ‘stone’ as an Anaxagorean uúsdpocs of the sun, (59 A 20a DK). Even in Aristotle it is uncertain sometimes (e.g., de Caelo 284a1) whether &pyatot refers to a Pre-Platonic philosopher or to anonymous sages of Urzeit. The charge of plagiarism in this case, however, would be very weak: the conformity of a philosophical theory to Urweisheit was usually desireable, like the argument e consensu omnium.

The oi uév in the last sentence of Aristarchus’ quotation almost certainly refer to Thales: cf. Diogenes Laertius I 24 np@tog dè Kai nv DOT <aTHV Qu >épav Tod unvos tpiaxóda einev (suppl. Scaliger). Diogenes’ report (together with I 27 on the 365-day year) is the only explicit evidence of Thales’ dealings with the lunisolar calendar, and the main Belegstelle for Nilsson’s theory which connects the origin of Greek calendar with the astronomical achievements of the Milesians. As it is now attested more than five centuries earlier, the theory itself gains some fresh support.!8 The notice does not mean, of course, that Thales ‘first used’)? the name tpiaKdc (which is known from Hesiod OD 766); it means that Thales first introduced (apparently in a calendar reform) the artificial custom to call tprakás last day of any month irrespective of whether it was ‘hole’ (29) or ‘full’ (30 days).?° Heraclitus (who is credited with some knowledge of Thales’ astronomy) speaks about the alternation of ‘incomplete’ (brnôuetpoc) and complete months in the new fragment cited immediately after Aristarchus.?' Thales and Solon are connected by legend, and both are credited with the regulation of the calendars in their cities. Solon is said to have named the last day of the month ¿vn kai véa (which is Attic) and Thales to have named it tpiakác (which is Ionic and common Greek).?? This looks to be a later construction, the two cogoi being ebperai of the local calendars; but if einev is interpreted as ‘fixed in official usage’, there is nothing unhistorical in this tradition. 18 M.P. Nilsson, ‘Die Entstehung und die religiöse Bedeutung des griechisches Kalendars’, Scripta minora (Lund 1960). Nilsson thought the reform was patronized by the Delphic Oracle (doubted by E.J. Bickerman, The Chronology of the Ancient World [London], p.23 of the Russian translation [Moscow, 1975]). 19 As is inaccurately stated in LSJ, s v tpiaxdc II, 1. Diogenes’ report cannot mean that Thales defined the length of the month as 30 days, either, contra C.J. Classen, Thales, Suppl X, (1965), col 943 63; first, because of the formulation (‘gave the name of triakas’); second because Thales must have been acquainted with the variability of the synodal month. 20 G. Unger, ‘Zeitrechnung der Griechen und Römer’, Handbuch des Altertumswissenschaffes Bd I (Nördlingen 1886), 563; A.C. Samuel, ‘Greek and Roman Chronology’, Hand. d. altertumswiss. I 7 (München 1972), 60, 115. tpıakdg is attested in Milesian inscription of the fourth century B C: SIG 286 13. 21 So I understand äAkot’ &Adacovoc pETaPaAAETal (sc. fuépas), GAAOTE TAEUVAC (col II, 46-7). 22 Plutarch Sol 25; DL I 59. On ¿wn kai véa see M.L. West, Hesiod's Opera, 770.

The connection of eclipses with noumenia must have been apparent to anyone who understood their true cause, and is emphasized in the parallel report of Cicero, Rep I 16 25 Z (not in DK): [Pericles heard from Anaxagoras] ... certo illud tempore fieri et necessario, cum tota se luna sub orbem solis subiecisset; itaque etsi non omni intermenstruo, tamen id fieri non posse nisi intermenstruo tempore ... quod Thaletem Milesium primum vidisse dicunt.’ The easiest way to explain the riddle of Thales’ prediction would be to suggest that according to his mpdyva@oic solar eclipses must necessarily occur certo tempore, i.e., TH tpiakdôt (at astronomical noumenia), for this is what is meant by the ‘prediction’ of eclipses in the case of Anaxagoras;? cf. also Geminus 5 TOD KATA GEATVHV Ayeıv AKPIBÖG Tac HweEpac rapaderyud ÉOTL TO TAG Tod NAiov ÉKAEÏYEL yivecbar Ti TpiaKkdÓr TÓTE YAP OUVOOELEL À CEA VN TO nAio. Aristarchus may have known this from tradition (divergent from that of Herodotus I 74 oòpov mpobépevos Eviavtov TODTOV) and interpreted tpiaxdg as Thales’ onuetov for the supposed Enitpdo8Eoic theory, though in fact the connection of eclipses with noumenia may have been empirically established long before the discovery of their true cause. Aristarchus’ report on Thales may have been continued by something like 6 u&v yap OaAtis npoeine tH tpiaxdòi EKAciyeE TÔV AALOV Tpiakdda Aéyov Tv vovunviav Kai Tv obvodov. And I wonder if Herodotus’ Énavtôv tOUTOV arose from the misunderstanding (or misreading) of Evnv taútnv, év 1] SE Kai ÉYÉVETO, i.e., ‘just that noumenia in which it actually occurred’.”4 Yet, is it probable that Thales was so GÉUvetoc as not to realize what he actually knew (oÙGÈ pabdvtses yiwaoKovol Heraclitus B 17)? émimpoo8_ecic is Aristarchus’ own term, but tpiaKads is not (cf. KaAodcıv). The latter term alone proves that Thales predicted eclipses (whatever was his exact method, and whether he could determine nv EKAEINTIKTHV tpiakdda or not) — that is, like an astronomer, by 23 Cf. DL II 8 33 npoeinev and II 16 25 vovpnviarc. 24 Diels’ suggestion (a.p. Guthrie, HGP I 47, n.2) that éviavtég is used here in its ‘original’ sense of solstice is based on Brugmann’s false etymology (from éviado): see P. Chantriane, Dictionnaire étymologique. de la langue grecque, 348 (connects with ôi-evoc etc.). The word probably had its classical meaning already in the Mycenean (enijausijo), cf. V.P. Kazanskene and N.N. Kazanskij, Predmetno-ponyatijnyj slovar’ greceskogo jazyka. Krito-mikenskij period (Leningrad 1986), 158. Besides, eclipses have nothing to do with solstices.

calculating the precise dates of noumeniai, not like a lucky charlatan, manipulating ‘Babylonian records’. Thales knew that solar eclipses had to do something with the moon cycle, that the moon somehow ‘participated’ in them and even determined them; Was it then so inconceivable for a clever Greek and the originator of the ratio naturalis to visualize this mysterious participation as physical intervention? To answer this question in affirmative we must wait for another scrap of papyrus, e.g., from Democritus’ ‘Astronomy’. Meanwhile, one thing is absolutely certain: the ascription of the &nınpöoßeoig theory of eclipses (which presupposes the ‘earthen’ nature of the moon) to Thales was not first made in the first century BC by ‘Posidonian’ doxography, as one might think hitherto. Aristarchus of Samos knew it and, as I have tried to demonstrate above, his source was the PrePeripatetic tradition of the fifth century BC. Center for Hellenic Studies and Department of the History of Philosophy Institute of Philosophy of the Academy of Sciences Volchonka 14 Moscow USSR 25 The hypothesis of ‘Babylonian records’ was first developed by Tannery, 62 sq. Since then it has been restated many times, quite recently in Kirk-RavenSchofield, 82. Such records, however, could only be used by a professional astronomer.