Masculine noun ὁ ἐραστής: «one who loves, lover» (active), opposed to τὸ ἐρώμενον (the beloved, passive). Phaedr. 227c–243e — the opposition ἐραστής (lover) / μὴ ἐραστής (non-lover) structures the three speeches; Symp. 178c–180b — Phaedrus exalts the ἐραστής–ἐρώμενος pair as the foundation of ἀρετή; Resp. V 474c–475c extends the metaphor: the φιλόσοφος is the ἐραστής of all σοφία.