Nine daughters of Jupiter and Mnemosyne, goddesses of poetry, history, and other arts and sciences. The paintings of Herculancum show all nine in their respective attributes. In the National-Museum of Paris is the famous collection with which Pius VI. enriched the Vatican. Lesueur left a celebrated picture of the same subject.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894