The original meaning is that the monarchs of the Zhou and Lu kingdoms have the same surname (meaning the same origin and are brotherly states).
Understanding the Kingdom of Lu, it was a vassal state of the Zhou Dynasty, founded by the descendant of the Duke of Zhou, the younger brother of King Wu of Zhou. The sons of Xibochang (Ji Chang), with Ji Fa and Ji Dan being the most virtuous, Ji Fa being King Wu of Zhou, and Ji Dan being the Duke of Zhou (i.e., the Duke of Zhou). In the early years of the Western Zhou Dynasty, the Duke of Zhou assisted his son, King Cheng of Zhou, in his eastward campaign to exterminate the Amam Kingdom, which had rebelled with Wu Geng, and King Cheng of Zhou sealed the eldest son of the Duke of Zhou, Bo Yu, in the Amam Kingdom's homeland, and established the State of Lu. The Duke of Zhou, as a founding member of the Zhou royal family and a royal relative, did his best to take care of everything for the Zhou dynasty from the time he assisted King Wu of Zhou. During the administrative period, he was also conscientious and did not dare to have the slightest negligence, in the Duke of Zhou's own admonition to go to the feudal state on the sealing of the Bo Bird said: "I am the son of King Wen, the younger brother of King Wu, and the uncle of King Chenggong, and I am not too lowly in this world. However, when I wash my hair once and hold it up three times, eat a meal and spit out the food three times, and get up to receive the scholars, I still worry that I will lose the world's wise men. When you come to Lu, don't be proud of your country. The idiom of "The Duke of Zhou spits out his food and the whole world returns to him" was thus left in later times. This is the idiom of "The Duke of Zhou spits, the whole world returns to him. Later, when the Duke of Zhou was seriously ill, he left a message saying, "When I die, you must bury me near Cheng Zhou, for I dare not leave King Cheng in the least. When the Duke of Zhou died, King Cheng buried him at Bi, the place where King Wen was buried. In this way, King Cheng showed that he did not dare to take Zhou Duke as his subject, and could only let Zhou Duke go to follow King Wen. Zhou Gong's life is probably a true depiction of the saying "Bow down and spare no effort, until death do us part".
Among the many states in the Zhou Dynasty, Lu was the "Zongbang" of the Ji family, and the "Wang Guo" of the vassals, so "there is nothing as dear to Zhou as Lu, and there is nothing as dear to Lu as Zhou". Lu has become a typical Zhou ritual preservation and implementation, the world said, "Zhou rituals in Lu carry on".