By some accounts, they were the daughters of Zeus and Mnemosyne (memory). Then again, perhaps they were children of the primordial deities Gaia and Uranus. At the same time, they were considered water nymphs.
The role of the Muses was inspiration in the arts and sciences. Nine in number, they each had a special area of expertise. Since they personified various arts, they were invoked by creators to provide inspiration for the creation of drama or poetry.
Nine Muses were enumerated by the Greek poet Hesiod, each symbolized by an object that represented her sphere. For instance, Clio, the Muse of History, held a scroll, while Terpsichore, who inspired dance, was symbolized by a lyre. In drama, the familiar comic and tragic masks represented Thalia and Melpomene respectively.
The Roman writer Varro, however, recognizes only three Muses, who represent practice, memory and song.