Jupiter falls in love with the nymph Callisto, a votary of the chaste goddess Diana, a guise that Jupiter, on the advice of Mercury, assumes, thereby achieving his purpose. Diana, meanwhile, falls in love with the shepherd Endymion and is angry when Callisto approaches her again, demanding her embraces. Juno, jealous of her husband's affairs, calls on the Furies, who turn Callisto into a bear, a metamorphosis at once reversed by Jupiter, who now wins Callisto's heart in truth, setting her finally among the stars.

Cavalli's opera won immediate success in Venice and has continued to do so in modern revivals. The tenor aria Cor mio, che vuoi tu? (My heart, what do you want?) and the mezzo-soprano Dolcissimi baci (Sweetest kisses) may be heard in recital repertoire.