PROLOGUE The scene is set in Arcadia. Natura and Eternita apostrophize those who have climbed the stony path to Parnassus. To them comes Destino demanding that they add Calisto to the names of those written in letters of stars in the heavens. They question this new addition, but Destino promises that it is by Giove’s decree and that her story will show Calisto’s right to immortality.

SCENE ONE A parched forest. The earth has been laid waste by wars; no water flows, no trees come into leaf. Giove, accompanied by Mercurio, has descended from Olympus to see what can be done to restore nature, but his attention is almost immediately diverted by the arrival of Calisto who, the daughter of the war-like Lycaon, has become a nymph of Diana by way of expiation. She laments the death of nature. Giove, seeing that he might accomplish two purposes in one, steps forward and promises miracles of restoration for certain rewards. Even with the miraculous evidence of the bubbling spring before her, Calisto denounces Giove as some rude lecher and departs, indignantly proclaiming her virtue. Giove is dumbfounded at the rebuff and immediately asks Mercurio to devise some means of accomplishing his amatory purposes. Mercurio suggests that, since Calisto follows Diana and Giove is all-powerful, he should transform himself into the semblance of Diana; Calisto will in any case return to the spring he has created for it is the only source of water in the forest. His prediction proves right and when Calisto does return she is overjoyed to find her ‘Goddess’ in an unusually affectionate mood and goes with ‘her’ willingly to explore other groves – and other things. Mercurio, left alone, has some cynical observations to make on the merits of deceit in love-making.

Endimione, attracted by the blossoming of nature in this corner of the forest comes to lament his unfulfilled love for the goddess Diana who soon arrives, together with a crotchety old nymph, Linfea, tracing the newly-flowing water to its source. It is clear that Diana is moved by Endimione but cannot show this in front of Linfea who chases the young man away from the Virgin Presence. Calisto re-enters, greatly contented by her exploration of the woods, and seeing Diana, expresses her ardor for her in terms which cause great indignation to the Goddess. Diana threatens her with expulsion from the order for indecency and departs in high anger. Calisto, not understanding, is heartbroken by the apparent change in her Goddess’ affection while Linfea is left to ponder on the dubious impulses which arise from time to time within her virgin bosom.

A little Satirino has been listening to Linfea and comes out to offer himself should she decide to give in to her impulses. This brings Linfea back with a start to her upright way of life and, showering him with insults about his birth (which makes the little Wood-God very angry), she repulses him and they part on the worst of terms. Diana now encounters Pane who declares his passion for her and his wish that she should join him as ruler of the Sylvan World. He also receives a sharp rebuff and is left, with the suspicion of a rival in Diana’s affections, to be comforted by his two henchmen, Sylvano and Satirino, and a chorus of wood-creatures.

SCENE ONE The Summit of Mount Latmos. Endimione sings to the moon of his love for Diana and finally falls asleep. She has followed him alone and, admiring the sleeping youth, dares to kiss him. Endimione dreams that he is holding Diana in his arms and awakes to find that it is true. She admits her love and, conscious-stricken for her vows of virginity, leaves him, but promises to return soon. The little Satirino, watchful on Pane’s account (as well as by natural inclination), makes some fairly acid comments on the frailty of virgin Goddesses and skips off to tell his master.

SCENE TWO The plain of Erymanthus. Giunone, suspicious of the long absence of Giove, comes to earth. She encounters Calisto and from her description of ‘Diana’s’ embraces is convinced that Giove has been up to no good. As luck will have it Giove (still in the form of Diana) and Mercurio come looking for Calisto and, not seeing Giunone, make another assignation on the nymph. As Calisto runs off Giunone reveals herself, but Giove decides to face it out and Giunone, almost convinced that her suspicions were right, leaves with scarcely veiled threats of retribution. Giove and Mercurio sing of the necessity of curbing wives who would interfere with their husbands’ pleasures until Endimione enters, ecstatically in love. He suddenly sees ‘Diana’ and rushes up to ‘her’ (causing Giove some moments of acute discomfort and Mercurio great amusement). Then, in burst Pane and his henchmen, led by Satirino. They take Endimione captive and he is heartbroken by the over-hasty retreat of ‘Diana’ who suddenly finds life in female guise somewhat too complicated. As Endimione is dragged away, Linfea enters. She has made up her mind to try out her impulses – Satirino decides to give her the ‘sweetest of all revenges’ for her previous insults, and with several of his companions sets about it.

SCENE THREE By the spring Calisto waits for ‘Diana,’ but Giunone and the Furies arrive and, amid incantations, transform her into a little bear. Giunone, consoled by her revenge, returns to the heavens.

SCENE FOUR In another part of the forest Endimione is being tortured by Pane. The real Diana arrives and, enraged at seeing her love captured, drives away the tormentors. In an extended scene Diana and Endimione vow eternal, chaste love.

SCENE FIVE The stars in the heaven call for Calisto, and Giove, now returned to his normal shape, finds the little bear that once was Calisto. The comedy on earth is ended and he takes her to Olympus where she will shine forever as Ursa Minor.