When China men make friends to a certain extent, they often take such a form to mark them, that is, they become sworn brothers with Jin Lan. The word "Jin Lan" comes from the Book of Changes: "Two people are one, and their profits are broken; Words of one heart stink like moss. " Jin Lan brothers are also called "brothers", "brothers in the league" and "dry buddies", and the process of becoming sworn is called "becoming sworn". The Modern Chinese Dictionary explains "becoming sworn" in this way: "Becoming brothers and sisters because of good feelings or the same purpose." It seems that there are generally two purposes to become sworn: one is to have a good relationship, such as Ruan Ji, Ji Kang and Dan Tao in the "Seven Sages of Bamboo Forest". When they met the first side, they were "like Jin Lan"; Second, it has the same purpose as * * *, and "Taoyuan Sanjieyi" is the best example. Liu Jiebai said: "Work together to help the poor, serve the country and the people, and live and work in peace and contentment." They fulfilled this promise with their lives.