The ancient Greeks used important and specific words to encompass huge, overarching, and vital themes in their literary and moral worlds. These are the most important themes of the Iliad:
Kleos: "glory." The type of fame and renown that a hero strives for through impressive feats and deeds. Your accomplishments told by other people, even after your death, mean more than anything. Achilles chooses kleos over a long, happy, and normal life.
Hubris: "pride." Specifically, the type of excessive ego that makes a human think they can best a god. Humans will always be punished for hubris.
Menis: "rage." So important that it is the first word of the Iliad in the original Greek. The first word of an epic poem signifies its greatest recurring theme. The rage of Achilles (for the loss of Briseis, and then the loss of Patrocles) is what drives the entire narrative. It determines the fate of all those fighting in the Trojan War. Most significantly, the word menis is traditionally ascribed to gods only. It does not describe normal human anger, but the wrath of a godlike figure.