§5.1Ἰσαῖος Χαλκιδεὺς; μὲν ἦν τὸ γένος, παραγενόμενος δʼ εἰς Ἀθήνας, καὶ σχολάσας· ʼ Λυσίᾳ κατά τε τὴν τῶν ὀνομάτων ἁρμονίαν καὶ τὴν ἐν τοῖς πράγμασι δεινότητα, ὥστʼ εἰ μή τις ἔμπειρος πάνυ τοῦ χαρακτῆρος τῶν ἀνδρῶν εἴη, οὐκ ἂν, διαγνοίη πολλοὺς τῶν λόγων ῥᾳδίως ὁποτέρου τῶν ῥητόρων εἰσίν.
Isaeus was by birth a Chalcidian, but having come to Athens, he studied under Lysias both in the harmony of his words and in his skill in practical matters, so that if one were not thoroughly experienced in the style of these men, one would not easily distinguish many of their speeches, to which of the two orators they belong.
ἤκμασε δὲ μετὰ τὸν Πελοποννησιακὸν πόλεμον, ὡς ἔστι τεκμήρασθαι ἐκ λόγων αὐτοῦ, καὶ μέχρι τῆς Φιλίππου ἀρχῆς παρέτεινε.
He flourished after the Peloponnesian War, as can be inferred from his speeches, and extended his career down to the reign of Philip.
καθηγήσατο δὲ Δημοσθένους, ἀποστὰς τῆς σχολῆς, ἐπὶ δραχμαῖς μυρίαις· διὸ καὶ μάλιστα ἐπιφανὴς ἐγένετο.
He became the teacher of Demosthenes, having withdrawn from his school, for a fee of ten thousand drachmas; which was the chief cause of his becoming famous.
αὐτὸς δὲ καὶ τοὺς ἐπιτροπικοὺς λόγους συνέταττε τῷ Δημοσθένει, ὥς τινες εἶπον.
He himself also helped Demosthenes compose the speeches against his guardians, as some have said.
καταλέλοιπε δὲ λόγους ἑξήκοντα τέσσαρας, ὧν εἰσι γνήσιοι πεντήκοντα, καὶ ἰδίας τέχνας.
He left sixty-four speeches, of which fifty are genuine, and also manuals of his own on the art.
πρῶτος δὲ καὶ σχηματίζειν ἤρξατο καὶ τρέπειν ἐπὶ τὸ πολιτικὸν τὴν διάνοιαν·
He was also the first to begin to use rhetorical figures and to turn his thought toward the political style; in which Demosthenes especially imitated him.
ὃ μάλιστα μεμίμηται Δημοσθένης μνημονεύει δʼ αὐτοῦ Θεόπομπος ὁ κωμικὸς ἐν τῷ Θησεῖ.
The comic poet Theopompus mentions him in his Theseus.