Theon of Smyrna: Book on Astronomy

and whom Plutarch expressly calls his companion1, the grammarian2 Theon.

In the dialogue On the E at Delphi3, Plutarch introduces this same companion Theon as discussing dialectical reason in oracles and mentioning in passing the oracle regarding the doubling of the cube, a subject also discussed by Theon of Smyrna4. But the arguments that Plutarch’s companion makes there are those of a grammarian filled with much erudition, which befit him perfectly.

Furthermore, we have found the following mentions which might seem to pertain to our author.
Among the ancient (palaious ancient) writers on the art of rhetoric, Theon the Platonist is mentioned by Joannes Doxopater5, who held that in oratorical descriptions, not only persons, things, times, and places should be expressed, as Hermagoras and Apsines desired, but also modes (tropous modes/manners). We do not believe, however, that this Theon the Platonist is the well-known author of the Progymnasmata Preliminary Exercises; but we do not know whether he is the same as our Theon of Smyrna.

It is even less certain regarding that Theon of whom Joannes Siculus6 says that one should not trust Theon and Sopater, concerning...

1 See Plutarch, Table Talk, I, 4; I, 9; IV, 3; VIII, 6, 8.
2 Ibid. I, 4; Cf. VIII, 6.
3 Ibid. I, 9; and VIII, 8.
4 Ch. v, p. 386 E.
5 Arithmetic, ch. 1.
6 In Homilies on Aphthonius, ch. XII, in Walz’s Greek Rhetoricians, vol. II, p. 513, line 25, and in Excerpts from the same Doxopater’s Commentary on Hermogenes’ On Invention, book I, in Cramer’s Greek Anecdotes from Oxford Manuscripts, vol. IV, p. 168, line 20.
7 Scholia on Hermogenes’ On Ideas, II, ch. 11, § 10, in Walz’s Greek Rhetoricians, vol. VI, p. 456, lines 1-4.