δέ without μέν.—A clause with δέ often has no correlative particle in the clause with which it is contrasted. Here μέν is not used because the opposition in the first clause was too weak, or because the speaker did not intend to announce a following contrast or did not think he was going to use a contrasted δέ clause. Sometimes the entire first clause may have to be supplied in thought from the general connection or from what has gone before. δέ without μέν in such cases is common in poetry, but not rare in prose, even in brief antitheses, as ἃ πάντες ἀεὶ γλίχονται λέγειν, ἀξίως δ' οὐδεὶς εἰπεῖν δεδύνηται exploits
a. When a relative construction passes over into a construction with a personal or demonstrative pronoun, the relative clause usually has no μέν. Cp. Soph. Aj. 457, quoted in 2517.
b. οἱ δέ, when opposed to a larger number of persons or things, is often used without οἱ μέν, as προεληλυθότες ἐπὶ χι_λόν, οἱ δ' ἐπὶ ξύλα
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].