Diodorus also states (Book I.18) that Osiris first recruited the nine Muses, along with the Satyrs or male dancers, while passing through Ethiopia, before embarking on a tour of all Asia and Europe, teaching the arts of cultivation wherever he went. The Muses, the personification of knowledge and the arts, especially literature, dance and music, are the nine daughters of Zeus and Mnemosyne (memory personified). Hesiod’s account and description of the Muses was the one generally followed by the writers of antiquity. It was not until Roman times that the following functions were assigned to them, and even then there was some variation in both their names and their attributes: Calliope (epic poetry), Clio (history), Euterpe (flutes and lyric poetry), Thalia (comedy and pastoral poetry), Melpomene (tragedy), Terpsichore (dance), Erato (love poetry), Polyhymnia (sacred poetry), Urania (astronomy). Three ancient Muses were also reported in Plutarch’s Quaestiones Convivales (9.I4.2–4). The Roman scholar Varro relates that there are only three Muses: one who is born from the movement of water, another who makes sound by striking the air, and a third who is embodied only in the human voice. They were Melete or Practice, Mneme or Memory and Aoide or Song.