μειλίχιον μῦθον
The semantic range of μειλίχιος when used to describe words or speech is a broad one. Kind or gracious words are used to persuade or encourage. The adjective modifies both muthos (used three times) and even more often epos (used nineteen times) in our texts. It is also used as a substantive with the verb προσηύδα (used three times) to indicate this kind of speech. These persuasive words are used between friends. The one context in which this is patently not the case is informative because it uses its antonym to indicate how unsuccessful such persuasion can be between enemies. At Iliad 11.137 two Trojans, Peisandros and Hippolokhos, beg Agamemnon in battle to ransom them as prisoners of war rather than kill them. The narrator says they use gracious speech in their request, but hear an ungracious voice in response (ὣς τώ γε κλαίοντε προσαυδήτην βασιλῆα / μειλιχίοις ἐπέεσσιν· ἀμείλικτον δ’ ὄπ’ ἄκουσαν, Iliad 11.136–137). Agamemnon refuses their pleas and kills them (compare Iliad 21.98 for a similar refusal also termed an “ungracious voice in response”).
As we will discuss further below (see 10.542), the semantic range of μειλίχιος also includes speech between friends in which the adjective is used with words of welcome (see also Odyssey 19.415 and 24.393). Similarly, Diomedes uses such words with Glaukos once he realizes that their grandfathers were guest-friends (Iliad 6.214).
This last example brings us to contexts where the words are used to address those who are, could be, or should be friends, but who either are or could be angry with or hostile to the speaker. For example, Helen speaks to Hektor this way when he comes to retrieve Paris, and her words are meant to show him her shame at her own conduct as well as that of Paris (Iliad 6.343; see Ebbott 1999 for more on the way Helen’s shame is portrayed in the Iliad). When Odysseus and Nausikaa see each other, he wonders what would be the best way to approach her: to supplicate her by taking hold of her knees, or stand further off and use gracious words (ἐπέεσσιν ἀποσταδὰ μειλιχίοισι, Odyssey 6.143). He decides on this second option because if he clasps her knees (naked as he is), she might get angry (Odyssey 6.145–147), and so he speaks a gracious and cunning speech (μειλίχιον καὶ κερδαλέον φάτο μῦθον, Odyssey 6.148), which, of course, he hopes will persuade her to help him.
In addition to these cases of such words meant to assuage or forestall someone’s anger, we have two final examples that are even closer to the case of Tydeus and therefore help us understand the traditional story behind his embassy to the Thebans. Odysseus speaks with such words to Ajax in the underworld, hoping to persuade his friend turned enemy to speak with him (τὸν μὲν ἐγὼν ἐπέεσσι προσηύδων μειλιχίοισιν, Odyssey 11.552). And Nestor proposes approaching Achilles with these kinds of words as well as with gifts to persuade him to return (δώροισίν τ’ ἀγανοῖσιν ἔπεσσί τε μειλιχίοισι, Iliad 9.113). Once we see the wide range of contexts in which this kind of speech can be used, we understand better that Tydeus is sent as a messenger to the Thebans in order to persuade them, and that he comes as a friend to friends who may nevertheless be hostile to him (as indeed they turn out to be). Tydeus comes on behalf of Polyneikes, of course, who was supposed to share the kingship of Thebes with his brother Eteokles. When Tydeus’ words of persuasion (presumably, urging him to follow this original arrangement) fail, he is later ambushed. The attack of the Seven against Thebes will be the next step. But we can infer that Tydeus’ speech, if we had an example of it from an ancient epic about the Theban war, would have started from a friendly stance and would have been gracious toward Eteokles and the Thebans.