Leonid Zhmud The Origin of the History of Science in Classical Antiquity

On Solstices and Equinoxes ascribed to Thales and mentioned by Dio-
genes Laertius (I, 23) before he cites Eudemus could hardly be among them.
48
Had Eudemus been familiar with this work and had he considered Thales its
author, our information on the ‘father of astronomy’ would have been much
fuller.
49
Meanwhile, the only discoveries Eudemus associates with Thales are
the prediction of a solar eclipse and the determination (a more precise one) of
solstices. The first discovery is mentioned in all three versions of Eudemus’ re-
port on Thales, the second in two of them. It is impossible to say for certain that
the
History of Astronomy credited Thales with no other discoveries. But these
discoveries constitute the most reliable part of the tradition, unlike, for
example, the advanced astronomical views attributed to Thales in Aëtius’ do-
xography.
50
According to Clement and Diogenes Laertius, Thales predicted (proeipe$n)
the eclipse; in Dercyllides–Theon (fr. 145) we find the following:
Qal4~ (sc. e0re prõto~) 1líou Ékleiyin kaì t3n katà tà~ tropà~ aÿtoñ
períodon, !~ oÿk Ísh @eì sumbaínei.
Thales (was the first to discover) the eclipse of the sun and the fact that the sun’s
period with respect to the solstices is not always the same.
48
As was supposed, e.g., by Tannery, P.
Recherches sur l’histoire de l’astronomie an-
cienne, Paris 1893, 21; Heath. Aristarchus, 20; Burkert. L & S, 416. The close pro-
ximity of these two reports does not imply their common origin: Diogenes is notori-
ous for his ‘mosaic’ technique of compilation. The work ascribed to Thales ap-
peared, most probably, in the third century BC: Classen, C. J. Thales,
RE Suppl. 10
(1965) 937.
49
Aristarchus of Samos, who expressly ‘quoted’ Thales’ words on when and why solar
eclipses occur (cf. above, n. 47), seemed to use this pseudo-epigraph. His passage is
preserved on the papyrus:
The Oxyrhynchus papyri, ed. by M.W. Haslam, Vol. 53,
London 1986. See Mouraviev, S. POxy 3710, col. II 33–55, III 1–19,
Corpus dei pa-
piri filosofici greci e latini, ed. by F. Adorno, Florence 1992, 229–242; Lebedev. Ar-
istarchus; Bowen, A. C., Goldstein, B. R. Aristarchus, Thales, and Heraclitus on
solar eclipses: An astronomical commentary on P. Oxy. 53.3710 cols. 2.33–3.19,
Physis 31 (1994) 689–729; Sider, D. Heraclitus on old and new months: P. Oxy.
3710,
ICS 19 (1994) 11–18.
50
See e.g.
Dox., 340.7 (division of the celestial sphere into five zones), 353.20 (expla-
nation of solar eclipses), 358.15 (explanation of lunar eclipses), 360b 14 (phases of
the moon), 376.22 (spherical shape of the earth).

---

2. Thales and Anaximander
241
Inasmuch as the ‘discovery’ of the solar eclipse can be understood not only as a
prediction but also as an
explanation thereof, a number of scholars are ready to
assign to Eudemus a report of Thales’ knowledge of the true cause of eclipses.
51
Though an assertion that Thales explained the eclipse of the sun occurs in many
post-classical sources, starting with Aristarchus of Samos,
52
this seems to me
quite improbable.
53
First, Thales turned from ‘predictor’ of eclipses in Herodo-
tus and Eudemus into its ‘first discoverer’ in Dercyllides–Theon only because
the entire list of astronomers’ achievements depends here grammatically on
e0re prõto~. Due to the abridgement and redaction of the original, pro-
eipe$n, attested in the other two versions, was left out, so that a ‘prediction’
turned into a ‘discovery’. The same corruption, though with a result diametri-
cally opposite, befell Eudemus’ evidence in Diogenes Laertius: prõto~ @st-
rolog4sai kaì 1liakà~ ëkleíyei~ kaì tropà~ proeipe$n – “Thales was the
first to study astronomy and to predict the solar eclipses and solstices” (I, 23). It
is obvious that the meaningless ‘prediction of solstices’ appeared due to the
loss of an appropriate verb (e.g., e0re ktl., as in Dercyllides–Theon) at
tropá~, which made it depend on proeipe$n.
54
Second, everything we know about Thales and Greek astronomy of the sixth
century suggests that he simply could not have had a theory offering a
correct
explanation of solar eclipses. Third, there is no reason to believe that Eudemus
attributed such a theory to Thales at all, unlike the prediction, attested by two of
the three sources. The ‘explanation’ implies knowledge that the moon, which
eclipses the disc of the sun, reflects, rather than emitting light. Now, according
to Dercyllides–Theon, Eudemus assigned the discovery of this fact (and the
theory of lunar eclipses as well) not to Thales, but to Anaximenes (fr. 145).
Most of the specialists, following an earlier and more reliable tradition, assume
that it is in fact Anaxagoras who is meant here. We will return to this question
later (7.4), concluding for now that we lack any evidence that would link the