The tragic descent of the hero-musician Orpheus to the underworld to retrieve his bride, and his performance at the court of Pluto and Proserpina, offered compelling material for librettists and composers of opera (see List of Orphean operas) and ballet. Pluto also appears in works based on other classical myths of the underworld. As a singing role, Pluto is almost always written for a bass voice, with the low vocal range representing the depths and weight of the underworld, as in Monteverdi and Rinuccini's "L'Orfeo" (1607) and "Il ballo delle ingrate" (1608). In their "ballo", a form of ballet with vocal numbers, Cupid invokes Pluto from the underworld to lay claim to "ungrateful" women who were immune to love. Pluto's part is considered particularly virtuosic, and a reviewer at the première described the character, who appeared as if from a blazing Inferno, as "formidable and awesome in sight, with garments as given him by poets, but burdened with gold and jewels."