§ 350 — D. B. Monro Grammar of the Homeric Dialect 0

δή is properly a temporal Particle, meaning now, at length (Lat. jam) : hence it implies arriving at a result, as ἐξ οὗ δὴ τὰ πρῶτα διαστήτην from the time that the point was reached when they quarrelled : εἰ δή if it has come to this that, and so if finally, if really. With Superlatives it expresses that the highest stage has been reached, as Il. 1. 266 κάρτιστοι δὴ κεῖνοι κτλ. these were quite (finally) the mightiest. So in questions, πῶς δή how has it come to be that—; and prohibitions, μὴ δή do not go so far as to—.

δή may begin a sentence in Homer, as Il. 15. 437 Τεῦκρε πέπον, δὴ νῶϊν ἀπέκτατο πιστὸς ἑταῖρος : and often in the combinations δὴ τότε (tum vero), and δὴ γάρ. The original meaning is best seen in these forms (where δή is emphatic), and in ἤδη (for ἦ δή), and ἐπεὶ δή.

As δή is one of the words which unite with a following vowel, so as to form one syllable, it is sometimes written δ', and so is liable to be confused with δέ. This occurs especially in the combinations δὴ αὖ, δὴ αὐτός, δὴ οὕτως : as Il. 1. 131 μὴ δὴ οὕτως, 340 εἴ ποτε δὴ αὖτε, 10. 385 πῆ δὴ οὕτως, 20.220 ὃς δὴ ἀφνειότατος κτλ. So in εἰ δ' ἄγε the sense generally requires δή : see § 321.

Note that δῆτα, δῆθεν (cognate or derivative forms) are post-Homeric ; as also are the combinations δήπου, καὶ δή.