 In "Metamorphoses" 11, Jupiter learns of the prophecy about a son born from Thetis, a sea god.The prophecy declared that the son of Thetis would achieve greater things than his father and would be considered greater than his father, which deeply frighten Jupiter.After the hearing the prophecy, Jupiter decided it would be best to have Peleus, Jupiter's mortal grandson, to take Thetis as a wife.