only Calliope carries the name that identifies the verbal shapes which poetry commands. She is pre-eminently the symbol of its operational command of the formulas. She therefore is reserved for the princely function.
Havelock argues that Calliope alone among the Muses signifies the technical mastery of verbal formulas and is thus uniquely suited to empower the political and judicial speech of princes in oral culture.
, Preface to Plato, 1963thesis