Allegorically Speaking

The Muses dancing with Apollo, by Baldassare Peruzzi

Mnemosyne was the personification of memory in Greek mythology This titaness was the daughter of Gaia and Uranus and the mother of the Muses by Zeus. In Hesiod's Theogony, kings and poets receive their powers of authoritative speech from their possession of Mnemosyne and their special relationship with the Muses. Zeus and Mnemosyne slept together for nine consecutive nights and thereby created the nine muses:

• Calliope (Chief of the muses and muse of epic poetry)
• Clio (muse of history)
• Erato (muse of erotic poetry)
• Euterpe (muse of lyric song)
• Melpomene (muse of tragedy)
• Polyhymnia (muse of sacred song)
• Terpsichore (muse of dance)
• Thalia (muse of comedy and bucolic poetry)
• Urania (muse of astronomy)

Mnemosyne was also the name for a river in Hades, counterpart to the river Lethe, according to a series of 4th century BC Greek funerary inscriptions in dactylic hexameter. Dead souls drank from Lethe so they would not remember their past lives when reincarnated. Initiates were encouraged to drink from the river Mnemosyne when they died, instead of Lethe. These inscriptions may have been connected with a private mystery religion, or with Orphic poetry (see Zuntz, 1971). Similarly, those who wished to consult the oracle of Trophonius in Boeotia were made to drink alternately from two springs called "Lethe" and "Mnemosyne". An analogous setup is described in the Myth of Er at the end of Plato's Republic. According to Pausanias in the later second century AD[2] there were but three original Muses: Aoide ("song" or "voice"), Melete ("practice" or "occasion") and Mneme ("memory"). Together, these three form the complete picture of the preconditions of poetic art in cult practice. In Delphi three Muses were worshipped as well, but with other names: Nete, Mesi, and Hypate, which are the names of the three chords of the ancient musical instrument, the lyre. Alternatively they were called Cephisso, Apollonis, and Borysthenis, whose names characterise them as daughters of Apollo. In later tradition, four Muses were recognised: Thelxinoe, Aoede, Arche, and Melete, said to be daughters of Zeus and Plusia (or of Uranus). One of the persons associated with the Muses was Pierus. By some he was called the father (by a Pimpleian nymph: called Antiope by Cicero) of a total of seven Muses, called Neilo, Tritone, Asopo, Heptapora, Achelois, Tipoplo, and Rhodia. [1] Though taken together, the Muses form a complete picture of the subjects proper to poetic art, the association of specific muses with specific art forms is a later innovation. The muses were not assigned standardized divisions of poetry with which they are now identified until late Hellenistic times. The canonical nine Muses, with their fields of patronage, as established since the Renaissance, are:

• Calliope (Chief of the muses and muse of epic poetry)
• Clio (muse of history)
• Erato (muse of erotic poetry)
• Euterpe (muse of lyric song)
• Melpomene (muse of tragedy)
• Polyhymnia (muse of sacred song)
• Terpsichore (muse of dance)
• Thalia (muse of comedy and bucolic poetry)
• Urania (muse of astronomy)

This information is from wikipedia