Peleus, who dwelt on Pelion, the mountain of Chiron, was aided by the wise Centaur. In vain Thetis played all the tricks of metamorphosis such as were used by the old sea-divinities against their assailants.
Kerényi interprets Peleus's seizure of Thetis as a cosmically mandated contest between mortal persistence aided by Chiron's wisdom and the elemental shape-shifting resistance of an archaic sea-goddess, with destiny overcoming divine autonomy.
, The Gods of the Greeks, 1951thesis