Aesacus’ father Priam has a funeral for Aesacus in Troy. His sons attend, except for Paris, who is in Greece. There, Paris soon kidnaps Helen, another man’s bride. Grecian soldiers sail after him, but they are delayed by a storm in Aulis where they hold a ceremony for Jupiter. When they are about to make a sacrifice, a serpent slithers up a tree over the altar and eats nine birds from a nest. A prophet proclaims that this means that the Greeks will conquer Troy, but only after nine years of war. Then the snake turns into marble.
The famous Trojan war begins when Paris kidnaps Helen from Greece. However, only when the prophet in Aulis foresees the entire scope of the Trojan War does it become clear that this war has been fated to occur since before it even began. This is another reminder that fate operates decisively in this world. Although it seems that Paris is responsible for starting the war, his actions precipitate a long-fated war.
When the storm continues, the prophet suggests that the Greeks sacrifice a virgin girl in order to appease Diana. A father at last decides to put the public before himself and agrees to sacrifice his daughter Iphigenia. Diana takes sudden pity on the girl and substitutes an animal for the sacrifice. The storm finally subsides, and the Greeks continue on their way to Troy.
Diana saves Iphigenia just before she is sacrificed, suggesting that Diana is motivated most of all by people’s willingness to appease her. She rewards this willingness by releasing people from their intended sacrifice.