The tale that explains the origin of the Trojan War in Greek mythology is the story of the Judgment of Paris. It involves a contest among the goddesses Aphrodite, Hera, and Athena for the title of the fairest. Paris, a prince of Troy, was chosen to decide the winner and, swayed by Aphrodite's promise of the most beautiful mortal, Helen, he chose her. This decision led to the abduction of Helen and ultimately sparked the devastating conflict known as the Trojan War, highlighting themes of desire, jealousy, and the consequences of choices.