Theon of Smyrna: Book on Astronomy

and de Gelder1 have brought forward regarding him, we do not believe that all these testimonies from the ancients truly pertain to him.

Certainly, our author is indeed Theon ho platōnikos Theon the Platonist, whose opinion regarding the lineage of Plato’s kinsmen Critias and Glaucon is refuted by Proclus2. Nor should it be doubted that our Theon is that "great mathematician, author of the work On the Four Mathematical Disciplines," as he was called by the Greek cardinal Bessarion3, who named him as a leader among those "interpreters of Plato who, in explaining his books, have spoken at length on mathematical principles."

However, it is by no means certain that our author is that Theon who is introduced by Plutarch in the dialogue On the Face in the Moon, who is a student of poets4 and of Aristarchus5—not the famous Samian mathematician, but the Alexandrian grammarian—and who argues against the opinion regarding the Moon's inhabitants more in jest than in earnest, though he is not ignorant of the threefold motion of the Moon in longitude, latitude, and altitude6, yet confesses that he knows nothing of solar and lunar eclipses beyond what children already know, and asks to be taught the rest by Lucius the Platonist7. He is also frequently encountered in Plutarch’s Table Talk, always speaking in a manner befitting a grammarian.

1 History of Mathematics, 2nd edition, vol. I, pp. 292-293.
2 On the Timaeus, p. 26 A, Greek edition of Basel; p. 58 of Schneider’s edition.
3 Against the Calumniator of Plato, ch. VIII. Venice, 1503.
4 See Plutarch, On the Face in the Moon, ch. VII, p. 923 F; ch. XIX, p. 931 E, F; and ch. XXV, p. 938 D.
5 Ibid. ch. XXV; p. 938 D.
6 Ibid. ch. XXIV.
7 Ibid. ch. XX, p. 932 D, E.