The State of Lu ultimately could not employ Confucius, nor did he seek an official position. He then devoted himself to collating texts and teaching, editing the Classic of Poetry (Shijing) and the Book of Documents (Shangshu), standardizing the Book of Rites (Liji) and the Book of Music (Yuejing), and compiling the Spring and Autumn Annals (Chunqiu).
Confucius's principle for organizing ancient cultural heritage, in his own words, was "to transmit rather than to create" ("to transmit rather than to create")—that is, to elucidate rather than to innovate. His attitude was one of "trusting and loving antiquity" (faith in and love for antiquity), preserving historical authenticity while doing so with a passion for ancient culture. He also stated that someone who makes assertions without investigating or mastering the material, without thoroughly clarifying the situation, is not a true scholar. He himself, he said, was different: he first sought out knowledgeable people to question, listened to their accounts, and selected those views that were both reasonable and well-supported; then he observed widely from multiple perspectives and recorded what he saw. In summary, his approach combined listening and observing.
From his youth, including during his travels through various states, Confucius carefully observed, collected, and studied ancient historical and cultural legends, artifacts, and related documents. These ranged from the eras of Yao and Shun (legendary sage rulers) to the Western Zhou and early-to-mid Spring and Autumn Period, including official records, temple documents, all ritual protocols, folk and aristocratic poetry, songs, music, tools for noble divination, and bamboo slips. The scope covered ancient society, politics, economy, military, diplomacy, culture, education, and human production and lifestyle—everything imaginable. After gathering these materials, he spent a long time and great effort, putting his heart into them. Through identification, classification, analysis, and synthesis, he finally compiled the Confucian "Six Arts" (Liu Yi)—the Classic of Poetry (Shi), Book of Documents (Shu), Book of Rites (Li), Book of Music (Yue), I Ching (Yi), and Spring and Autumn Annals (Chunqiu). In doing so, he synthesized ancient Chinese history and culture, establishing a milestone that carried forward the past and opened the way for the future in the history of Chinese thought.
The *Classic of Poetry* (Shijing) primarily consists of folk songs from the Western Zhou period and a portion of song-and-dance music from the ruling class's life. In ancient times, there were over three thousand poems in the *Classic of Poetry*. Confucius removed duplicates, selecting only those that could be applied to Li (Propriety) and Yi (Righteousness), retaining about three hundred pieces. Confucius said, "The three hundred poems can be summed up in one phrase: 'Thought without depravity.'" "Thought without depravity" means that there is nothing in their ideological content that is not "pure and upright"—that is, what was preserved was all connected to social effects and political functions, as he stated: "They can be used to inspire, to observe, to foster community, to express grievances; near at hand, to serve one's father; far away, to serve one's lord; and one can learn the names of many birds, animals, plants, and trees." He compiled the *Book of Documents* (Shangshu) by "tracing the rites of the Three Dynasties to prepare for the Kingly Way," writing from the political perspective of the "Kingly Way" and the Way of Ren (Benevolence). The *Book of Rites* (Liji) comprises the ritual systems of the Xia, Shang, and Zhou dynasties, compiled and ordered based on the Duke of Zhou's surviving works on rites. Confucius compiled the *Classic of Music* (Yuejing), retaining what he believed could cultivate genuine, good, and beautiful emotions and provide catharsis, while deleting what he considered bad. He said, "Correcting the music so that the *Ya* and *Song* odes each found their proper place." The *I Ching* (Book of Changes) is said to have been deduced and summarized by Fu Xi and King Wen of Zhou based on the *He Tu* (River Chart) and *Luo Shu* (Luo River Writing). Through his compilation, Confucius also created commentaries such as the *Tuan* and *Xiang*, eliminating mysterious views about ghosts and spirits, and emphasizing the objective laws of human affairs and nature. As for the *Spring and Autumn Annals* (Chunqiu), he revised the historical records of the State of Lu, which contained chronicles of domestic and international events and the words and deeds of rulers and ministers, with the idea of "using the brush and eraser, praise and blame, to establish laws for future rulers," infusing it with his political and social views. He later said to Yan Hui (his most beloved disciple), "In the past, I compiled the *Poetry* and *Documents*, rectified the *Rites* and *Music*, intending to govern the world and leave teachings for future generations—not merely to cultivate myself or govern the State of Lu alone."
His "Six Arts" (Liu Yi: rites, music, archery, charioteering, calligraphy, mathematics) were also used in teaching. He said to his disciples: "When you arrive in a state, its customs and education can be known. If its noble people are gentle and sincere, it is the effect of the teaching of the Classic of Poetry (Shijing); if they understand affairs and know the successes and failures of ancient history and politics, it is the effect of the teaching of the Book of Documents (Shangshu); if they are broad-minded, generous, kind, and approachable, it is the merit of the teaching of the Classic of Music (Yuejing); if their words and deeds are in accord with human feelings and they examine problems calmly and subtly, it is the effect of the teaching of the I Ching (Book of Changes); if they are respectful, frugal, solemn, and reverent in dealing with people and affairs, it is the effect of the teaching of the Book of Rites (Liji); if they can integrate theory with practice and handle matters well, it is the effect of the teaching of the Spring and Autumn Annals (Chunqiu, the historical records of various states)." Confucius also observed the shortcomings that arose in the transmission of these ancient texts. He told his disciples: "The flaw of the Classic of Poetry is foolishness; the flaw of the Book of Documents is exaggeration and falsehood; the flaw of the Classic of Music is extravagance; the flaw of the I Ching is believing in ghosts and spirits, using divination to determine human affairs, causing words and deeds to deviate from or violate objective laws, resulting in harming others without benefiting oneself; the flaw of the Book of Rites is being overly numerous and troublesome; the flaw of the Spring and Autumn Annals is being dogmatic and conservative in handling state affairs, not conforming to the objective reality of social development and change, which can provoke popular resistance and internal conflicts among the noble class."