1 The Birth of Science - MSRI

10.5 A Passage of Seneca 253
The Almagest sentence just quoted appears in the chapter that introduces
the study of planetary motions. Ptolemy claims there that he was the first
to create a planetary theory, and his statement about Hipparchus (the only
scientist mentioned at that point) is an essential part of his priority claim.
In devoting a good chunk of prose to the non-existence of a Hipparchan
planetary theory, Ptolemy must have been attacking an existing belief that
Hipparchus had at least started to formulate such a theory. Otherwise,
how to explain that a scientist about to treat a scientific topic should devote
so much space to a predecessor of three centuries earlier that had not
indeed studied the subject?
The idea that the Almagest included all earlier astronomical knowledge
may be tautologically based on the fact that, because of the loss of older
works, earlier astronomy was reconstructed based on the Almagest. And
we do know that certain Hellenistic astronomical ideas do not appear in
the Almagest: if nothing else, heliocentrism and the infinite universe. We
have seen in Sections 3.6 and 3.7 that there is good reason to think that,
contrary to common opinion, these were not isolated notions that were
abandoned abruptly.
Thus a reasonably accurate picture of Hellenistic astronomy as it existed
in Hipparchus’ time will depend crucially on analyses of the literature
preceding the Almagest.
10.5 A Passage of Seneca
Seneca wrote:
Of these five stars, which display themselves to us and which pique
our curiosity by appearing now here now there, we have recently
started to understand what their morning and evening risings are,
where they stop, when they move on a straight line, why they move
backward; we learned a few years ago whether Jupiter will rise or page 316
sink or retrograde (for this is the name given to its backward movement).
89
88 Ptolemy, Syntaxis mathematica, III, i, 207 (ed. Heiberg). Rehm was the first person to correctly
interpret this passage of the Almagest, and Toomer is confident of this interpretation:
[Ptolemy/Toomer], p. 139, note 25.
89 “Harum quinque stellarum, quae se ingerunt nobis, quae alio atque alio occurrentes loco curiosos
nos esse cogunt, qui matutini vespertinique ortus sint, quae stationes, quando in rectum
ferantur, quare agantur retro, modo coepimus scire; utrum mergeretur Iupiter an occideret an retrogradus
esset (nam hoc illi nomen imposuere cedenti), ante paucos annos didicimus.” (Seneca,
Naturales quaestiones, VII, xxv, 5).
Revision: 1.11 Date: 2003/01/06 02:20:46