During the Spring and Autumn period, Guan Zhong and Bao Shuya were close friends. Guan Zhong was often unlucky in business and made political missteps, but Bao Shuya always defended him, believing in his talent. When Guan Zhong later became prime minister, he remarked, 'My parents gave me life, but Bao Shuya truly understands me.'

Their bond was so deep that people said they were 'like liver and gall shining on each other' — completely open and trusting. This story later became the source of the idiom, symbolizing the highest form of friendship.