Why does Zhouyi have Confucius' explanation?

Because in his later years, Confucius began to pay attention to Zhouyi.

When Confucius was young, he disdained the Book of Changes and didn't understand Heaven. He just wants to travel around the world and conquer the world with his personal talents. However, in the face of skinny reality, he hit a wall again and again and felt like a lost dog. However, after the ups and downs of his life and all kinds of disappointments, his attitude towards the Book of Changes has changed greatly, and he can't let go when he is old.

The silk book unearthed in Mawangdui records that "the master is old and easy, living in a chair and walking in a bag", which shows that Confucius' Yi learning has reached the point of forgetting to eat and sleep, and even "reading Wei Sanjue" has broken the cowhide rope of bamboo slips many times.