The various legends concerning Achilles' invulnerability are wildly contradictory. The most famous relates to his mother, Thetis, dipping him into the River Styx but failing to fully submerge the heel by which she held him--thus, the Achilles heel legend. Other tales relate that Thetis bathed her son in ambrosia and then burned him with fire--also creating an invulnerable state. Other stories, including Homer's The Iliad, mention that Achilles was wounded more than once in battle, which would seem to rebuke the invulnerability aspect entirely. In any case, there seems to be no mention that Thetis told her son of this special condition, and Achilles' ferocity in battle appears to be due to his boldness--not because of a knowledge of his own invulnerability.