Xu Shu was much valued by Liu Bei for his strategic talents. After several victories on the battleground against Cao Cao, Xu was made the chief military advisor. Cao Cao was greatly surprised at the news. "If you want this person," one of his advisors said, "you can bring his mother to Xuchang and send a forged letter in his mother's handwriting, asking Xu Shu to desert Liu Bei and come here. As Xu is well-known for a strong filial  affection, surely he will come." This plot worked. For Xu, on receiving the letter, cried tearfully, asking Liu Bei for an immediate departure. Feeling sad, though, Liu persisted in his stay for another night, during which the two aired their sad feelings. The next day Liu laid a banquet outside the city for Xu. Holding the latter's hand, Liu said,  "After we separate today, only heaven knows when and where we will meet again." He wept bitter tears. After setting off on his way, Xu suddenly turned his horse and returned. "I almost forgot an important matter." He said to Liu. "Ten kilometers from Xiangyang City, in a place called Long zhong, there is a talent called Zhuge Liang. Do you want to meet him?" Liu expressed his willingness at once, but also aired doubt about whether Zhuge Liang was as talented as Xu. "He tells positions of stars in the heavens," Xu assured him, "and recognizes everything on earth. He knows a person's real nature at the first meeting----the number one talent under the heaven. If you have him as your military advisor, you'll have the country under your name." Liu suggested a visit to Zhuge by Xu on his behalf. At this, the latter shook his head in disapproval. "You must go and offer your invitation personally, and his acceptance depends entirely on your sincerity." With these words said, Xu turned his horse and left. Later, Liu paid three trips to Zhuge's straw house, another favorite story among Chinese people. The text is developed in the order of   _  .
space logic time cause and result