The Ancient Greek infinitive is a non-finite verb form, sometimes called a verb mood, with no endings for person or number, but it is (unlike in Modern English) inflected for tense and voice (for a general introduction in the grammatical formation and the morphology of the Ancient Greek infinitive see here and for further information see these tables).
It is used mainly to express acts, situations and in general "states of affairs"[1] that are depended on another verb form, usually a finite one.
It is preceded by the neuter singular article (τό, τοῦ, τῷ) and has the character and function of both a noun and a verbal form.
A so-called dynamic infinitive may be governed by verbs of will or desire to do something (ἐθέλω or βούλομαι "to be willing, wish to", εὔχομαι "pray, wish for", κατεύχομαι "pray against, imprecate curse to", αἱροῦμαι "choose, prefer to", μέλλω "to be about to, or: delay to", κελεύω "urge, command to", ἐπιτάσσω "order to", ψηφίζομαι "vote to", ἐῶ "allow to", δέομαι "beg to" etc.
), verbs of will or desire not to do anything (δέδοικα/δέδια "fear to", φοβοῦμαι "be afraid to", ἀπέχομαι "abstain from doing", αἰσχύνομαι "be ashamed to", ἀπαγορεύω "forbid to", κωλύω "hinder, prevent" etc.)
It can also be found after adjectives (and sometimes derived adverbs) of kindred meaning (δεινός "skillful", δυνατός "able", οἷός τε "able", ἱκανός "sufficient, capable" etc.).
[19] So, in cases as those presented in the following examples, a dynamic infinitive somehow recalls a corresponding finite mood expressing will or desire, pray or curse, exhortation or prohibition etc.
The latter means that it represents a corresponding finite verb form of the oratio recta (of the direct speech or discourse),[23] thus a declarative infinitive denotes both tense and aspect or stage of action.
Yet in the last two examples another reading is also possible, considering ἀποδιδόναι and ἀποδοῦναι to be present and aorist declarative infinitive respectively: "I swear that I give (always, or in any relevant situation etc.)
[39] Note: a "declarative" infinitive is sometimes the mood of subordinated clauses in indirect speech, instead of a corresponding indicative (either a realis or conditional irrealis one) or optative mood, in modal assimilation to the main infinitive used to represent the independent clause of the direct speech; so after relative, temporal or conditional conjunctions such as: ὃς "who" or ὅστις "whoever", ἐπεὶ or ἐπειδή "since, when", ὅτε "when", εἰ "if" etc.
[40] An example: Here, the main infinitives, those directly depended on the finite verb ἔφη, namely πορεύεσθαι and ἀφικνεῖσθαι, attractivelly affect the mood of the embedded clauses introduced by ἐπειδὴ, a temporal conjunction, and ἐν ᾧ, a relative prepositional phrase.
This construction can be used as an indirect speech mechanism, in many instances interchangeable with a complementary declarative clause introduced by "ὅτι/"ὡς"[47][48] (or a supplementary participle).
(Articulated substantive as subject of the finite verb would have been put in nominative case) Oratio recta/Direct speech would have been: ἡNOM ἡμετέρα φύσιςNOM ἱκανωτέραNOM ἐστὶFIN τῆς ὑπὸ τῶν θεῶν προκριθείσης.
(Articulated substantive -subject of the finite verb- and predicate adjective both in nominative case) And here is an example where no indirect speech is involved: This construction, accusative and infinitive, is also always in place when the main verb is an impersonal one or an impersonal verbal expression, and the infinitival clause functions as its subject (here also there is no indirect speech).
As fas as the two first are concerned, traditionally this construction is sometimes called (in Latin terminology) dativus cum infinitivo or genitivus cum infinitivo (dative with the infinitive or genitive with the infinitive respectively) and is considered to be a case attraction,[65][66] the dative or genitive being used instead of a predicate in the accusative: ἄνδρα, ὡς προθυμότατον; see also below.
On the other hand, as it is indicated by predicate adjectives/sunstantives or participial constituents of the infinitival clause, it is not unusual at all for an accusative to be understood and be supplied by context as the subject of the infinitive, as the following examples illustrate.