Passage 2.8.6
Ἄρατος δέ, ὥς οἱ τὰ ἐν Πελοποννήσῳ προεκεχωρήκει, δεινὸν ἡγεῖτο Πειραιᾶ καὶ Μουνυχίαν, ἔτι δὲ Σαλαμῖνα καὶ Σούνιον ἐχόμενα ὑπὸ Μακεδόνων περιοφθῆναι, καὶ---οὐ γὰρ ἤλπιζε δύνασθαι πρὸς βίαν αὐτὰ ἐξελεῖν---Διογένην πείθει τὸν ἐν τοῖς φρουροῖς ἄρχοντα ἀφεῖναι τὰ χωρία ἐπὶ ταλάντοις πεντήκοντα καὶ ἑκατόν, καὶ τῶν χρημάτων συνετέλεσεν αὐτὸς Ἀθηναίοις ἕκτον μέρος. ἔπεισε δὲ καὶ Ἀριστόμαχον τυραννοῦντα ἐν Ἄργει δημοκρατίαν ἀποδόντα Ἀργείοις ἐς τὸ Ἀχαϊκὸν συντελεῖν, Μαντίνειάν τε Λακεδαιμονίων ἐχόντων εἷλεν. ἀλλὰ γὰρ οὐ πάντα ἀνθρώπῳ τελεῖται κατὰ γνώμην, εἰ δὴ καὶ Ἄρατον κατέλαβεν ἀνάγκη γενέσθαι Μακεδόνων καὶ Ἀντιγόνου σύμμαχον· ἐγένετο δὲ οὕτως.
But Aratus, as his power in the Peloponnese advanced, considered it intolerable that Peiraeus and Munychia, as well as Salamis and Sunium, were still held by the Macedonians. Since he had no hope of taking these strongholds by force, he persuaded Diogenes, who commanded the Macedonian garrison, to surrender them for one hundred and fifty talents, of which sum Aratus himself contributed a sixth on behalf of the Athenians. He likewise convinced Aristomachus, who ruled as tyrant in Argos, to restore democracy to the Argives and thus align the city with the Achaean League; moreover, he also captured Mantineia, then controlled by the Lacedaemonians. However, not all things turn out according to man's intentions, for necessity compelled even Aratus himself to enter into alliance with the Macedonians and Antigonus. This came about in the following manner.