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

Aristarchus, 134ff.; Dicks. Early Greek astronomy, 92ff.
188
See above, 97, 253 n. 104.
189
Special treatises on astronomy were written by Oenopides, Meton, Euctemon, and
Democritus. Philip continued the tradition of compiling the parapegmata started by
Meton (see above, 102f.).
190
Cleostratus, Matricetas, Phaeinos, and Meton (
De sign. 4 = DK 6 A 1). Censorinus
says that, between the time of Cleostratus and Eudoxus, the octaëteris was improved
by Harpalus, Nauteles, and Menestratus (
De die nat., 18.5 = 6B4 DK); of these, only
Harpalus is known to us as an engineer and astronomer (ca. 480). See
DK I, 42n.;
Diels, H.
Antike Technik, Berlin 1920, 4; Heath. Aristarchus, 292f.

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6. From Meton to Eudoxus. ‘Saving the phenomena’
271
ture quality of his theories are totally at variance with the idea that this science
stagnated during the preceding four decades. In this period, observation yields
more and more empirical data that contradict the Pythagorean idea of the regu-
lar circular movement of celestial bodies. The most important of these data are:
the anomaly in the sun’s movement discovered by Meton and Euctemon; the
deviation of the moon and the planets from the plane of the ecliptic; the retro-
grade movements and stops of the planets on their way along the ecliptic; and
differences in planetary brightness indicating differences in their distances
from the earth. These anomalies led Eudoxus to develop a theory of homocen-
tric spheres, based on his own vast observations, as well as on a brilliantly con-
ceived kinematic model.
191
Before going back to Eudemus’ testimony concerning Eudoxus’ program of
‘saving the phenomena’ (which Sosigenes ascribed to Plato), we have to look
into the origin of two notions important to Plato, namely the uniform circular
movement of the planets and their divine nature, to which they owe the perfect
circularity of their orbits.
192
The first idea is attested in Philolaus, but goes back
to the earlier Pythagorean astronomy.
193
Ascribing the circular movement,
postulated by Anaximander for the sun and the moon, to the ecliptical motion
of the planets as well, the Pythagoreans must have aspired to bring the move-
ment of all heavenly bodies under the same principle, rather than to do justice to
empirical observations. The circle being at the time the only figure that could
account for the movements of the planets from a
geometrical point of view,
their numerous deviations from circular orbits were simply ignored. The same
geometrical logic demanded that this circular movement had to be uniform,
since even much later Greek astronomy could not deal mathematically ad-
equately with an irregular movement without reducing it to a combination of
several uniform movements.
194
Anaximander, in turn, postulated the daily cir-
191
To be sure, Eudoxus’ model could not account for the varying distances of the plan-
ets, though Polemarchus seemed to be aware of them (see above, 233).
192
Crat. 397c–d; Leg. 885e, 886e, 887e. A still more detailed argument for the divine
nature of heavenly bodies is to be found in the
Epinomis (986e 9f.). Aristotle, dis-
cussing the circular movement of heavenly bodies, also used a combination of meta-
physical and theological arguments, which were to be repeated until the end of An-
tiquity (
Met. 1072a 6f., 1073a 36–39; Cael. 269a 3–270b 30; Mete. 339b 20–27;
fr. 12 Rose).
193
Zhmud.
Wissenschaft, 214f., 218ff. As a matter of fact, the circular movement of the
planets follows from their order as established by the Pythagoreans: otherwise the
latter is meaningless. See also Geminus’ evidence: “The hypothesis underlying the
whole astronomy is that the sun, the moon and the five planets circulate at uniform
speeds in the direction opposite to that of the heavenly sphere. The Pythagoreans
were the first to approach such questions, and they assumed that the motions of the
sun, the moon and the five planets are circular and uniform.” (
Eisag. I, 19). It is un-
likely that Geminus should have projected onto the Pythagoreans what Eudemus as-
cribed to Eudoxus (Mittelstraß,