During the Southern and Northern Dynasties (420-589), there lived a beautiful, intelligent princess name Lechang in the State Chen. She and her husband Xu Deyan loved each other dearly. But before long their country was in danger of being invaded by the troops of the Sui Dynasty.
Princess Lechang and Xu Deyan had a premonition that their county would be occupied by the invaders and they would have to leave the palace and go into exile. During the chaos they might lose touch with each other. They broke a bronze mirror, a symbol of the unity of husband and wife into two parts and each of them kept a half. They aGREed that each would take their half of the mirror to the fair during the Lantern Festival, which is on the 15th day of the first Lunar month, in the hope that would meet again. When they were united the two halves would join together. Soon their premonition came true. During the chaos of war, the princess lost touch with her husband was taken to a powerful minister Yang Su's house and was made his mistress.
At the Lantern Festival the next year, Xu Deyan took his half of the mirror to the fair. He hoped that he could meet his wife. It so happened that a servant was selling the other half of the bronze mirror. Xu Deyan recognized it immediately. He asked the servant about his wife. As he heard about her bitter experience, tears rolled down his cheeks. Xu Deyan wrote a poem on the half of the mirror kept by his wife: "You left me with your broken mirror Now the mirror is back but not you I can no longer see your reflection in the mirror Only the bright moon but not you" .
the servant brought back the inscribed half of the mirror to princess Lechang. For days, she could not help sobbing because she knew her husband was still alive and that he missed her but they could not meet forever.
the minister, Yang Su, found this out. He was also moved by their true love and realized
it was impossible to get Lechang's love. So he sent for Xu Deyan and allowed the husband and wife to reunite.
From that story comes the idiom "A broken mirror joined together".It is used to suggest the happy reunion of a separated couple.