Why is Jiang Taigong's fishhook straight?

During the Yao and Shun period, the descendants of Emperor Yan were sealed in Lu in April for helping Dayu control water. At the end of Shang Dynasty, a very talented old man named Jiang came out of Lu State, taking the country name as his surname, also known as Lu Shang. At the end of Shang Dynasty, several generations of monarchs were either bad kings or tyrants, so the merchants of Lu were full of knowledge but had nowhere to display. In this way, many years have passed, and Lu Shang is over 70 years old, but he is still looking for an opportunity to show his skills. At this moment, Xibe Jichang in the Western Zhou Dynasty was recruiting wise men. Lu Shang arrived immediately after hearing the news, but he didn't go to see Xibochang immediately, because he knew that if he wanted to attract people's attention, he had to be reserved. So he went fishing by Ziquan River, a tributary of Weihe River, and waited quietly for the opportunity. One day, Xi Bochang went out hunting and divined as usual before going out. As a result of divination, this time I went out and got not rare birds and animals, but a talent who helped the country. Xibochang was dubious, but he began to pay attention along the way. When I came to the north bank of Weishui, I found a white-haired old man sitting there fishing with great dignity. He stood behind him for a long time, but he didn't catch any fish. The old man kept sitting still. Later, Xi Bochang found that the old man's hook was straight. Xi Bochang felt very strange and said, "How can a straight hook fish be hooked?" The old man said, "People who want to take the bait." This old man is Lu Shang. The old man talks with Xi Bochang and Kan Kan. Xibochang was extremely happy to hear Lu Shang's incisive analysis of the world situation. He felt that Lu merchants were saints who could make the Zhou Dynasty prosperous. Therefore, he asked himself to bring Lu Shang into the palace with a whip and made him a Buddhist, known as the "squire king" in history. Ty Wang Gong is very capable. He gave many ideas for Xibochang, which greatly enhanced Zhou's strength and prestige. After Xibochang's death, Zhou Wuwang addressed Lu Shang as "teacher and father" and was more obedient to him. Under the planning of Lu merchants, Zhou Wuwang finally overthrew the Shang Dynasty and established the Zhou Dynasty. Because of Lu Shang's greatest contribution, he was sealed in Qi State (Linzi, Shandong Province) and enjoyed the right to conquer neighboring vassal states. Lu Shang's posthumous title was that his descendants ruled Qi for more than 600 years.