διά

1. διά with the Genitive

a. Local: through and out of (cp. Hom. διέκ, διαπρό), as δι᾽ ὤμου ἔγχος ἦλθεν the spear went clear through his shoulder Δ 481, ἀκοῦσαι διὰ τέλους to listen from beginning to end Lyc. 16. Through, but not out of: διὰ πολεμίᾱς (γῆς) πορεύεσθαι to march through the enemy's country X. Hi. 2.8 and often in figurative expressions: διὰ χειρὸς ἔχειν to control T. 2.13, διὰ στόματος ἔχειν to have in one's mouth (be always talking of) X. C. 1.4.25 (also ἀνὰ στόμα).

b. Temporal: of uninterrupted duration, as διὰ νυκτός through the night X. A. 4.6.22, διὰ παντός constantly T. 2.49.

c. Intervals of Space or Time: διὰ δέκα ἐπάλξεων at intervals of ten battlements T. 3.21, διὰ χρόνου after an interval L. 1.12, intermittently Aes. 3.220, διὰ πολλοῦ at a long distance T. 3.94.

d. Other relations: Means, Mediation (per): αὐτὸς δι᾽ ἑαυτοῦ ipse per se D. 48.15, διὰ τούτου γράμματα πέμψᾱς sending a letter by this man Aes. 3.162. State or feeling: with εἶναι, γίγνεσθαι, ἔχειν, of a property or quality: διὰ φόβου εἰσί they are afraid T. 6.34, δι᾽ ἡσυχίᾱς εἶχεν he kept in quiet 2. 22, ἐλθεῖν ἡμῖν διὰ μάχης to meet us in battle 2. 11, αὐτοῖς διὰ φιλίᾱς ἰέναι to enter into friendship with them X. A. 3.2.8. Manner: διὰ ταχέων quickly T. 4.8.

2. διά with the Accusative

a. Local: of space traversed, through, over (Epic, Lyric, tragic choruses): διὰ δώματα through the halls A 600; διὰ νύκτα Θ 510 is quasi-temporal.

b. Cause: owing to, thanks to, on account of, in consequence of (cp. propter, ob): διὰ τοὺς θεοὺς ἐσῳζόμην I was saved thanks to the gods D. 18.249, τῑμώμενος μὴ δι᾽ ἑαυτόν, ὰλλὰ διὰ δόξαν προγόνων honoured, not for himself, but on account of the renown of his ancestors P. Menex. 247b. So in εἰ μὴ διά τινα (τι) had it not been for in statements of an (unsurmounted) obstacle: φαίνονται κρατήσαντες ἂν τῶν βασιλέως πρᾱγμάτων, εἰ μὴ διὰ Κῦρον it seems they would have got the better of the power of the king, had it not been for Cyrus I. 5.92.

c. διά is rarely used (in place of ἕνεκα) to denote a purpose or object: διὰ τὴν σφετέρᾱν δόξαν for the sake of their honour T. 2.89, δι᾽ ἐπήρειαν for spite D. 39.32 (cp. διὰ νόσον ἕνεκα ὑγιείᾱς on account of disease in order to gain health P. Lys. 218e).

d. διά with gen. is used of direct, διά with accus. of indirect, agency (fault, merit, of a person, thing, or situation). διά with gen. is used of an agent employed to bring about an intended result; διά with accus. is used of a person, thing, or state beyond our control (accidental agency). (1) Persons: ἔπρᾱξαν ταῦτα δι᾽ Εὐρυμάχου they effected this by the mediation of Eurymachus T. 2.2, τὰ διὰ τούτους ἀπολωλότα what has been lost by (the fault of) these men D. 6.34. The accus. marks a person as an agent not as an instrument. (2) Things: νόμοι, δι᾽ ὧν ἐλευθέριος ὁ βίος παρασκευασθήσεται laws, by means of which a life of freedom will be provided X. C. 3.3.52, διὰ τοὺς νόμους βελτῑ́ους γιγνόμενοι ἄνθρωποι men become better thanks to the laws 8. 1. 22. Sometimes there is little difference between the two cases: δι᾽ ὧν ἅπαντ᾽ ἀπώλετο D. 18.33, δι᾽ οὓς ἅπαντ᾽ ἀπώλετο 18. 35.

N.—διά with gen. ( = through) is distinguished from the simple dative ( = by): δι᾽ οὗ ὁρῶμεν καὶ ᾧ ἀκούομεν P. Th. 184c.

e. For διά with accus. to express the reason for an action, the dative is sometimes used (1517): τοῖς πεπρᾱγμένοις φοβούμενος τοὺς Ἀθηναίους fearing the Athenians by reason of what had happened T. 3.98. The dative specifies the reason less definitely than διά with the accusative.

f. When used in the same sentence, the dative may express the immediate, διά with the accus. the remoter, cause: ἀσθενείᾳ σωμάτων διὰ τὴν σῑτοδείᾱν ὑπεχώρουν they gave ground from the fact that they were weak through lack of food T. 4.36.

g. διά with accus. contrasted with ὑπό with gen.: φήσομεν αὐτὸ δι᾽ ἐκεῖνα ὑπὸ τῆς αὑτοῦ κακίᾱς ἀπολωλέναι we shall say that it (the body) is destroyed on account of those (remoter) causes (as badness of food) by its own evil (immediately) P. R. 609e.

3. διά in Composition

Through, across, over (διαβαίνειν cross), apart, asunder (διακόπτειν cut in two, διακρῑ́νειν discernere, διαφέρειν differ, διαζυγνύναι disjoin), severally (διαδιδόναι distribute).

δια- often denotes intensity, continuance, or fulfilment (διαμένειν remain to the end, διαφθείρειν destroy completely). δια- is common in the reciprocal middle (1726), as in διαλέγεσθαι converse; often of rivalry (οἱ διαπολῑτευόμενοι rival statesmen, διακοντίζεσθαι contend in throwing the javelin).