The two fates of Achilles

Here, Achilles tells us that his mother, Thetis, has presented him with two fates (9.498).

In short, if he remains in Troy and fights, then he’ll die—but his glory will never end.

If he sails home, his pride and glory die, but he’ll have a long life.

The choice grants a good amount of structure to the Iliad and informs the reader of what motivates Achilles.

Moreover, the passage is an antecedent to Plato's Symposium, in which Diotima explains that man's natural love, eros, seeks different forms of immortality.

The appetitive part of the soul seeks immortality through begetting children.

The spirited (thumos) part of the soul seeks immortality through fame and glory.

This presents a general map of the choice before Achilles in Book Nine and helps reveal what animates his rage.