Semele was the daughter of Cadmus and Harmonia, and the mother, by Zeus, of the god Dionysus. Because Zeus slept with Semele secretly, Hera only found out about the affair after the girl was pregnant. Bent on revenge, Hera disguised herself and persuaded Semele to demand that Zeus come to her in all the splendor with which he visited Hera. As a result, Semele asked Zeus to grant an unspecified favor, and got him to swear by the river Styx that he would grant it. Unable to break his oath, Zeus came to her armed in his thunder and lightning, and Semele was destroyed. However, Zeus rescued the unborn child from the mother's ashes and sewed it in his thigh until it was ready to be born. Thus Dionysus is sometimes called "the twice-born." Dionysus was raised at first by Semele's sister and brother-in-law, Ino and Athamus, and later by the nymphs of Nysa. As an adult, he retrieved his mother from Hades and made her a goddess; she was called Thyone.