Confucius made significant contributions to the "Book of Changes" or "Yi Jing." Regarded as the "Crown of the Three Mysteries" by Taoism and the foremost of the "Five Classics" by Confucianism, the "Yi Jing" owes its current status to Confucius.

In his later years, Confucius developed a strong interest in the "Book of Changes" and extensively studied chapters such as "Tuan," "Xici," "Xiang," "Shuo Gua," and "Wen Yan." He frequently employed the "Yi Jing" for divination purposes. On one occasion, when he received the hexagram "Fire over Mountain," he consulted his student Shang Qu for interpretation. Shang Qu acknowledged Confucius's wisdom but pointed out his lack of authority and status. Deeply moved, Confucius considered it to be a heavenly arrangement.

Devoting a significant portion of his energy to studying the "Book of Changes," Confucius's extensive reading resulted in the repeated cracking of his bamboo slips. His study of the "Yi Jing" went beyond its divination function, incorporating his understanding of the universe, social ethics, and interpretation of the text. In response, Confucius wrote ten articles known as the "Ten Wings" or "Yi Zhuan," including "Tuan" (Appended Judgments), "Xiang" (Images), "Wen Yan" (Words and Images), "Xi Ci" (Appended Statements), "Xu Gua" (Sequence of Hexagrams), "Shuo Gua" (Explaining the Hexagrams), and "Za Gua" (Miscellaneous Hexagrams). These writings formed the "Zhou Yi" into two parts, the "Classic" (Jing) comprising the hexagram figures, names, judgments, and line explanations, and the "Explanations" (Zhuan) providing interpretations of the Classic. Confucius's efforts established the "Book of Changes" as the first classic of the Confucian school.

However, during the Song Dynasty, Ouyang Xiu questioned the authorship of Confucius in writing the "Ten Wings." He criticized the complexity and inconsistencies within chapters such as "Xi Ci," "Wen Yan," and "Shuo Gua," suggesting they were not Confucius's works. This led to centuries of doubts and even questioning the entirety of the "Ten Wings" as Confucius's creation. Nonetheless, in 1973, bamboo slips discovered in the Han Dynasty tomb at Mawangdui provided evidence of Confucius's close association with the "Book of Changes." These slips recorded the thoughts and statements of Confucius and his disciples on the "Yi Jing," confirming his indispensable contribution.

Confucius's greatest contribution to the "Book of Changes" lies in diminishing the emphasis on divination and elevating it to a wide-ranging study of virtue and principles. In the Zhou Dynasty, the "Book of Changes" was primarily used for divining fortunes, focusing on numerical techniques. However, Confucius's research integrated his understanding of the universe, human life, and societal ethics, bringing vitality to the otherwise dry and mystical symbols. During the Han Dynasty, Confucian scholars embraced and extensively referenced the content of the "Ten Wings," elevating the "Book of Changes" to a "pure, subtle, precise, and profound" discipline. It was renamed as the "Book of Changes" (Yi Jing) and became the foremost among the Five Classics.

However, the Confucian and Taoist perspectives on the "Book of Changes" are not entirely aligned. During the pre-Qin era, Confucius sought counsel from Laozi and held him in high regard. Both Confucianism and Taoism consider the "Book of Changes" as a "sacred book" and an important source for their philosophical schools. The difference lies in their respective emphases.

In summary, the "Book of Changes" is like a city, with some departing through the eastern gate and others through the western gate, forming different branches. Some delve into ethical and moral discussions, grounded in practicality, while others explore the philosophical aspects of cosmic principles, becoming more abstract. Additionally, some scholars combine the "Book of Changes" with military strategy, medicine, music, and other fields, resulting in diverse research traditions. Different scholars and schools have proposed their own interpretations and commentaries, making the "Book of Changes" a work of enduring controversy and multiple perspectives. Both Confucianism and Taoism's profound appreciation and study of the "Book of Changes" highlight its significant position in ancient Chinese thought and culture. Even today, the "Book of Changes" continues to be extensively studied and cherished as one of the treasures of human wisdom.