E.C. Marchant, Commentary on Thucydides: Book 3

ἰδίᾳ—in contrast with what the government was doing κοινῇ.

κατά—often of the motive or reason, e.g. II. 87 ξυμπαραγενομένων κατὰ φιλίαν.

πρόξενοι—the fact that there were more representatives of Athens than one at Mytilene might show that the office was hereditary in a family, but more probably the title of πρόξενος καὶ εὐεργέτης had been granted by Athens to members of different Mytilenean families. Aristotle in Pol. 1304 a says that Dexander ἦρξε τῆς στάσεως καὶ τοὺς Ἀθηναίους παρώξυνε πρόξενος ὤν: he had a private quarrel with a member of the aristocratic party; from this small matter πολλῶν ἐγένετο ἀρχὴ κακῶν. In any case it would have been the duty of the Proxenus to inform Athens of movements in Mytilene unfavourable to her interests even before the war; but doubtless the quarrel was now an exasperating motive to him, and led directly to the outbreak of stasis, for it was a dispute about property and intermarriage between families of the opposed parties.

ξυνοικίζουσι—i.e. attempting to make the island into a single πόλις under one government, and in this case, an oligarchy.

ξυγγενῶν — Lesbos being of Boeotian (Aeolic) origin. To intervene on behalf of kinsmen was under all circumstances deemed justifiable among Greek states.

εἰ μή τις—‘unless they mean to,’ the fut. indic. marking the urgency; cf. VIII. 91 εἰ μή τις ἤδη φυλάξεται.