The particle ἄν (Hom. κέν, κέ) limits the meaning of the moods. It has two distinct uses:
a. In independent clauses: with the past tenses of the indicative and with the optative; also with the infinitive and participle representing the indicative or optative.
b. In dependent clauses: with the subjunctive.
No separate word can be used to translate ἄν by itself; its force varies as it modifies the meaning of the moods. In general ἄν limits the force of the verb to particular conditions or circumstances (‘under the circumstances,’ ‘in that case,’ ‘then’).1763
In Homer ἄν is preferred in negative, κέν, κέ in relative, sentences.1764
Position of ἄν.—ἄν does not begin a sentence or a clause, except after a weak mark of punctuation, as τί οὖν, ἄν τις εἴποι, ταῦτα λέγεις ἡμῖν νῦν; why then (
a. So with οὐκ οἶδ' ἂν εἰ (or οὐκ ἂν οἶδα εἰ) followed by a verb to which ἄν belongs:
οὐκ οἶδ' ἂν εἰ πείσαιμι
Repetition of ἄν.—ἄν may be repeated once or twice in the same sentence.
a. ἄν is placed early in a sentence which contains a subordinate clause, in order to direct attention to the character of the construction:
δοκοῦμεν δ' ἄν μοι ταύτῃ προσποιούμενοι προσβαλεῖν ἐρημοτέρῳ ἂν τῷ ὄρει χρῆσθαι
b. For rhetorical emphasis ἄν is added to give prominence to particular words: τίς γὰρ τοιαῦτ' ἂν οὐκ ἂν ὀργίζοιτ' ἔπη κλύων;
ἄν without a Verb.—ἄν sometimes stands without a verb, which is to be supplied from the context. So in the second member of a sentence with coördinate clauses: οἶδα ὅτι πολλοὺς μὲν ἡγεμόνας ἂν δοίη, πολλοὺς δ' ἂν (δοίη)
a. So with ὡς ἄν, ὥσπερ ἂν εἰ ( cross2480): παρῆν ὁ Γαδά_τα_ς δῶρα πολλὰ φέρων, ὡς ἂν (
ἐξ οἴκου μεγάλου
b. κἂ_ν εἰ is often used for the simple καὶ εἰ ( cross2372) and without regard to the mood of the following verb; sometimes there is no verb in the apodosis to which the ἄν may be referred, as
ἔστιν ἄρα τῇ ἀληθείᾳ, κἂ_ν εἰ μή τῳ δοκεῖ, ὁ τῷ ὄντι τύραννος τῷ ὄντι δοῦλος
Omission of ἄν.—ἄν is sometimes omitted when it may be supplied from the preceding sentence or clause. So often with the second of two verbs that are connected or opposed: τί ἐποίησεν ἄν; ἢ δῆλον ὅτι ὤμοσε (ἄν);
οὔτ' ἂν οὗτος ἔχοι λέγειν οὔθ' ὑ_μεῖς πεισθείητε
Subjunctive with ἄν.—Conditional, relative, and temporal clauses requiring the subjunctive must have ἄν, which is more closely attached to the conditional, relative, and temporal words than it is to the subjunctive.
a. Hence the combinations ἐά_ν (ἤν, ἄ_ν) on which cp. cross2283; ὅταν, ὁπόταν, ἐπήν (ἐπά_ν), ἐπειδάν from εἰ, ὅτε, ὁπότε, ἐπεί, ἐπειδή ἄν. When the particle does not thus coalesce, it is usually separated only by such words as μέν, δέ, τέ, γάρ.
b. The force of ἄν with the subjunctive cannot usually be expressed in English. For ἄν in final clauses with ὡς, ὅπως, and ὄφρα, see cross2201. In Hom. ἄν (κέν) is found in dependent clauses, 2334 c.
Herbert Weir Smyth [n.d.], A Greek Grammar for Colleges; Machine readable text [info] [word count] [Smyth].