Suda, s.v. Theognis,[=ii .692 Adler]

“Theognis of Megara, from Megara in Sicily. He lived around the time of the 59th Olympiad [ c/ 540 BCE]. He composed elegy for those who were saved from the Syracusans during the siege, around 2800 elegiac proverbs, a group of elegiac advice addressed to his lover Kyrnos, and other kinds of advisory lines. Theognis is useful because he wrote advice, but in the midst of this are interwoven foul and pederastic erotic lines too and many other things rejected by clean living.”

Θέογνις, Μεγαρεύς, τῶν ἐν Σικελίᾳ Μεγάρων, γεγονὼς ἐν τῇ νθ΄ ὀλυμπιάδι. ἔγραψεν ἐλεγείαν εἰς τοὺς σωθέντας τῶν Συρακουσίων ἐν τῇ πολιορκίᾳ, γνώμας δι᾿ ἐλεγείας ὡς (εἰς ed. pr.) ἔπη ̗βω΄, καὶ πρὸς Κύρ<ν>ον τὸν αὐτοῦ ἐρώμενον γνωμολογίαν δι᾿ ἐλεγείων, καὶ ἑτέρας ὑποθήκας παραινετικάς, τὰ πάντα ἐπικῶς (ἔπη ̗βω΄ Ditzen). ὅτι μὲν παραινέσεις ἔγραψε Θέογνις, <χρήσιμος·> ἀλλ᾿ ἐν μέσῳ τούτων παρεσπαρμέναι μιαρίαι καὶ παιδικοὶ ἔρωτες καὶ ἄλλα ὅσα ὁ ἐνάρετος ἀποστρέφεται βίος.

Harpocration 126-7

Theognis: This dude is Megarian, from Megara in Attica. The poet says this himself [783]. Plato didn’t acknowledge this when he claimed in Laws Book 1 that Theognis was from MEgara in Sicily. Not a few have followed Plato in this.”

Θέογνις· οὗτος δ᾿ ἦν Μεγαρεύς, ἀπὸ τῶν πρὸς τῇ Ἀττικῇ Μεγάρων. αὐτὸς γάρ φησιν ὁ ποιητής (v. 783). ὃ μὴ ἐπιστήσας Πλάτων ἐν α΄ Νόμων (test. 2) τῶν ἐν Σικελίᾳ Μεγαρέων πολίτην ἔφασκεν. κατηκολούθησαν δὲ τῷ Πλάτωνι οὐκ ὀλίγοι.

Stobaeus, 4.29.53

“This is what Xenophon says about Theognis: “The words of Megarian Theognis: This poet has composed about nothing else except for human excellence and wickedness. This poetry is a treatise on people, as if an equestrian were to write about horses.”

Ξενοφῶντος ἐκ τοῦ περὶ Θεόγνιδος. “Θεόγνιδός ἐστιν ἔπη τοῦ Μεγαρέως” (22–23). οὗτος δὲ ὁ ποιητὴς περὶ οὐδενὸς ἄλλου λόγον πεποίηται ἢ περὶ ἀρετῆς καὶ κακίας ἀνθρώπων, καί ἐστιν ἡ ποίησις σύγγραμμα περὶ ἀνθρώπων, ὥσπερ εἴ τις ἱππικὸς ὢν συγγράψειεν περὶ ἱππικῆς.