Greek · early 2nd century CE

Expositio rerum mathematicarum

ad legendum Platonem utilium; Greek: Tōn kata to mathēmatikon chrēsimōn eis tēn Platōnos anagnōsin; astronomical part

A handbook of the mathematics useful for reading Plato, whose astronomical part largely follows Adrastus of Aphrodisias. It explains the progressions, stations and retrogradations of the five planets, shows that the eccentric and epicyclic models are equivalent, and closes (Hiller 189–198) with stations, retrogradations, occultations and eclipses. Its rule for where stations occur is geometrically wrong: it puts them at the planet's greatest elongation from the centre of its epicycle, which would hold only if the epicycle stood still.

Author: Theon of Smyrna
Date: early 2nd century CE
Original language: Greek
Key term: προήγησις proēgēsis ('leading': Theon's word for retrogradation; its opposite, ὑπολείπεται, “trails”, means moving eastward, i.e. direct)
Kind: Theory / model
Planets: Mercury, Venus, Mars, Jupiter, Saturn

On the shelf · Greece and Rome · 13−1800 → 2026

−1800−1500−1000−5001500100015002026

Date · early 2nd century CESame shelf

Editions

2 editions.

Year	Edition	©
1878	Theonis Smyrnaei philosophi Platonici Expositio rerum mathematicarum ad legendum Platonem utilium, ed. E. Hiller, Leipzig: Teubner, 1878	PD
1892	Théon de Smyrne, Exposition des connaissances mathématiques utiles pour la lecture de Platon, tr. J. Dupuis, Paris: Hachette, 1892	PD

PD public domain

Read it

One digitised copy.

Hiller's 1878 Teubner edition, Greek textInternet ArchivePDOpen ↗

References

A. Jones, 'Translating Greek Astronomy: Theon of Smyrna on the Apparent Motions of the Planets', in Translating Writings of Early Scholars (De Gruyter, 2016) 465–505

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