In Book I, the initial quarrel between Agamemnon and Achilles, mediated by Nestor, is paralleled at the end of the book by the quarrel between Zeus and Hera, mediated by Hephaistos. The quarrel among the gods breaks down into a humorous scene that ironically accentuates the seriousness of the human quarrel. Homer's technique of repeating an earlier scene with a later one is used throughout the Iliad. In fact, this structural technique is a basis for the entire work. However, Book I essentially sets up the tension for the rest of the poem. The wrath of Achilles seems justified from Book I to Book IX. Achilles' wrath is held up for criticism from Book IX to Book XVIII. And finally there is reconciliation in Books XVIII and XIX. This pattern repeats in Books XIX through XXIV. Achilles wrath is justifiable in Book XIX to Book XXII. His wrath is criticized in Books XXII to Book XXIV. And finally, there is reconciliation in Book XXIV when Achilles and Priam meet.
Book I opens with the words, "Rage — Goddess, sing the rage of Peleus' son Achilles." Homer invokes the muse ("Goddess") of epic poetry to aid him in telling the story of Achilles' anger and the great war for Helen and Troy. He further introduces in the word "rage" one of the human qualities, along with pride and honor, that will make up a major theme of the work as a whole. Initially, Achilles' anger seems a reasonable response to the arrogance of Agamemnon, but as the poem progresses, it becomes clear that righteous anger can degenerate into petty resentment or escalate into uncontrollable rage. The necessity for reason and self-control over emotions becomes an overriding idea in the Iliad.
