R. G. Bury, The Symposium of Plato

ἐπὶ τὸν ὀκρίβαντα. It seems to have been usual for the poet, as well as the players and choreutae, to appear before the audience, wearing crowns but not in costume, at the προαγών of the great Dionysia held in the Odeum of Pericles on the 8th of Elaphebolion: see Aesch. III. 67 (Schol.), Ar. Vesp. 1109 (Schol.). The ὀκρίβας was apparently a platform (βῆμα, cp. Ion 535 E) in the Odeum, and not, as formerly supposed, the λογεῖον or stage in the theatre itself (cp. Smith D. A. II. 813 b, 818 b): Schol. ὀκρίβαντα: τὸ λογεῖον, ἐφ᾽ οὗ οἱ τραγῳδοὶ ἠγωνίζοντο. τινὲς δὲ κιλλίβαντα τρισκελῆ φασίν, ἐφ᾽ οὗ ἵστανται οἱ ὑποκριταὶ καὶ τὰ ἐκ μετεώρου λέγουσιν. Another meaning of ὀκρίβας is a painter's “easel.”

μέλλοντος ἐπιδείξεσθαι. The force of μέλλοντος is seen when we remember that the ἀνάβασις of the poets took place at the προαγών, before the actual performance of the play. For ἐπιδείκνυσθαι of theatrical displays, cp. Ar. Ran. 771 ὅτε δὴ κατῆλθ᾽ Εὐριπίδης, ἐπεδείκνυτο τοῖς λωποδύταις κτλ. With Agathon's self-assurance cp. Isocr. Paneg. 43 C μικρὸν ὑπὲρ ἐμαυτοῦ θρασυνάμενος...ποιήσομαι τοὺς λόγους.

οὕτω θεάτρου μεστὸν. This means “theatri applausu inflatum esse” (Stallb.); rather than “stage-struck,” cp. Themist. 26. 311 B; Synes. de provid. 105 B θεάτρου καὶ ἀγορᾶς ἄπληστος.