Who is Muses from Theogony and Works and Days and what is their importance?

The Muses are the nine daughters of Zeus and Mnemosyne: Cleio, Euterpe, Thaleia, Melpomene, Terpsichore, Erato, Polyhymnia, Urania and Calliope. Calliope is the most respected because she feeds dew to princes who find favor with the gods. The Muses, along with Apollo, give singers as a gift to mankind in order to make men forget their sorrows when they hear the songs about men of old and the gods. The Muses inspire Hesiod with a divine voice and tell him the history of the gods. The Muses live on Mount Olympus.