Mnemosyne — Classical Greek Myth Library

Homeric Achilles is the best of the Achaeans by speed, strength, and divine favor—not by impervious flesh. Later classical lore, however, told how Thetis tried to strip her mortal son of mortality. In one strand (Apollodorus; cf. Demeter’s treatment of Demophon in the Homeric Hymn), she hid the infant in the fire by night and anointed him with ambrosia by day to burn away his mortal part; Peleus spied her, cried out, and she abandoned the unfinished rite—leaving Achilles mortal still, or only partly tempered—and returned to the sea. Apollonius recalls Thetis’s nocturnal fire-care of the child. A second, famous strand (fully narrated in Roman Statius and scholia, rooted in Greek handbook tradition) has Thetis dip the baby in the Styx, holding him by the heel (or ankle); the immersed body becomes invulnerable, but the dry spot where her fingers gripped remains the place of death—hence the arrow of Paris/Apollo at Troy. Greek tragic and cyclic sources for Achilles’ death emphasize Apollo’s agency and Paris’s shot to a vulnerable spot without always theorizing a Styx baptism; the dip is the explanatory myth that reconciles divine motherhood with a single fatal weakness. Both variants express the same maternal logic: Thetis, forced to bear a mortal, tries to undo mortality and fails—by interruption (fire) or by incomplete immersion (Styx)—so that Achilles remains glorious and doomed.