These deities were nymphs of the mountain and the waters. Hesiod in Theogony narrates: “Mnemosyne slept in Pieria with the son of Saturn and gave birth to these virgins. For nine nights in a row, the wise Zeus went up to his sacred bed, slept next to the Memorial, away from all the immortals. "After a year, when the seasons and the months had completed their cycle and when many days had passed, Mnemosyne gave birth to nine daughters, all of whom were enchanted by music". Their names are: Klio, Efterpi, Thalia, Melpomeni, Terpsichore, Erato, Polymnia, Ourania, Kalliopi.