Neptune over the seas, and Pluto over the Underworld. Flora, the gods and the different peoples of the earth celebrate the peace (Air: "Ah! que la paix nous promet de douceurs") as Spring reawakens. They express gratitude for their happiness to Jupiter (Chorus: "Heureux vainqueur, le ciel, la terre et l'onde"). Act 1 Scene: The stage shows the shore of the Isthmus of Corinth, where the Isthmian Games are about to be celebrated. On either side are woods; the sea is in the background. The act begins as the day is breaking. Neptune arrives at the Isthmus of Corinth disguised as a Greek mortal. He reveals the reason to his follower Palémon: he is no longer a fickle god but is deeply in love with the nymph Naïs (Air "Je ne suis plus ce dieu volage"). Palémon tells Neptune that Naïs and the Corinthians are celebrating the Isthmian Games in the god's honour that very day. Neptune says that he does not want Naïs to respect him as a god but to love him for his own merits, which is why he is disguised as an ordinary mortal. He leaves the stage and Naïs arrives. She rejects the advances of Télénus, leader of the Corinthians, saying his love makes him too gloomy (Air:"J'ai trop connu par vos soupirs"). The festival begins with a chorus celebrating Neptune ("Chantons le Dieu des Eaux"). Naïs watches the games from a throne as a ballet figuré (figurative ballet) depicts boxing, wrestling and a foot race. At the end, Naïs awards a crown to the victorious wrestler. Suddenly, a fleet of shining boats appears - it is the sea gods in disguise bringing Neptune to the games. They sing the praises of Neptune and Naïs ("Chantons Naïs, chantons le dieu des mers"). Naïs is uncomfortable to hear her name linked with the god's in this way but the disguised Neptune continues his flattery of her (Ariette: "Tout cède aux charmes de tes yeux"). The disguised sea gods compete for the prize in the dance. Télénus is consumed with jealousy for his new rival. Act 2 Scene: The background portrays a mountain with woods, waterfalls, flowery paths etc. At its foot the entrance to a grotto is visible: on either side are asymmetrical trees whose thick-leaved branches create cradles of foliage. Naïs, has come to consult her father, the blind prophet Tirésie, in his secluded home