The expression “(on) this day” has an extremely pregnant meaning in different contexts of early Greek poetry. It is used in rituals and in solemn utterances, but it is much more than an emphatic way of saying “today.” It shows that the speaker is recognizing that a decisive, irreversible moment is approaching. Such knowledge of the appointed destiny is only accessible to the gods or to mortals inspired by them, which often makes the authoritative utterance “this day” a performative speech-act (...) that brings immediate accomplishment. The study of the instances of this expression, both with ἦμαρ and ἡμέρα, in epic, religious poetry, and tragedy, also sheds light on the different Greek notions of what a decisive day was. (shrink)