The renaissance of Confucianism was a direct reaction against the long prevailing of philosophical Daoism since the end of the Han Dynasty and the power of Buddhism during the time of North-South division and the early Tang Dynasty. Tang scholars saw not only their own position as state advisors endangered, but they were afraid the influence of the foreign religion of Buddhism on Chinese government and the social traditions. Buddhism is a religion with a very complex metaphysical philosophy, an aspect that the old Confucianism totally ignores. The aim of Tang and Song time Confucian writers was to find a system that was able to explain the universe and the position and behaviour of man in a way that could cope with the sophisticated Buddhist philosophy.
The most important Tang scholars defending Confucianism against the influence of Daoism and Buddhism were Han Yu 韓愈 (768-824) and Li Ao 李翱 (772-841). Han Yu, a great essayist of his time, vehemently argued against Buddhism and proposed to go back to the roots of human ethics, studying and interpreting the Confucian Classics. His main concern about Buddhism was that the foreign religion was egalitarian and did not observe the proper relation between senior and junior persons, and thereby destroyed the social order. In his essay "Sourcing the Way" 原道 (Yuandao), he wrote that humanity (ren 仁) and righteousness (yi 義) are the source of an overall social way under Heaven, unlike the "Way" of Daoism and Buddhism where everybody is seeking his own salvation. Human nature, Han Yu wrote in his essay "Sourcing human nature" 原性 (Yuanxing), can be divided into three classes: good, bad, and middle. The middle nature can move to both sides, being formed by humanity, rites, trust, righteousness and knowledge. Human nature (xing 性) is being laid into a person during his/her birth, while the seven emotions (qing 情) are produced according to the environment. Han Yu was a great protagonist of the Old Literature Movement (guwen yundong 古文運動) whose representatives wrote in the old simple and highly expressive style rather than in the complicated, rhymed and obscure style that has become popular during the time of North-South division.
Li Ao himself studied the Buddhist philosophy in order to be able to attack it. His most important writing is the book "Revival of the human nature" 復性書 (Fuxingshu), with the implicit meaning of "Revival (fusheng 復生) of Confucianism", as in Li Ao's eyes, the human nature (xing 性) is given us by birth (sheng 生). Every human nature is of equal quality, that means that everybody has the potential to become a saint like the mythological emperors Yao and Shun. It is only the emotions (qing 情) that mislead the true good nature of man. Both Han Yu and Li Ao have adopted the teachings of Mengzi 孟子, but they developed the thinking of the old philosopher to a more complex view of human behaviour.
It took time for the early re-interpreters of Confucianism to gain ground. It was the early Song Dynasty writer and politician Ouyang Xiu 歐陽修 (1007-1072) who stressed that the traditional Confucian cultural norms and education of the rulers by means of teaching them the old books and presenting them new writings, especially historiographical writings, all serve to practice a better policy. For that reason, he renounced the histories of Tang and Five Dynasties and instead wrote a new History of Tang (Xintangshu 新唐書) and a new History of Five Dynasties (Xin Wudaishi 新五代史), both books in an educating style to teach an imperial reader. A similar view had Sima Guang 司馬光 (1019-1086), who wrote the "Comprehensive mirror Providing Material for Government" 資治通鑑 Zizhi Tongjian, a historiography with a style highly oriented at the classical "Spring and Autumn" Annals (Chunqiu 春秋).
Also going back to the old classics, Zhou Dunyi 周敦頤 (1017-1073) was highly interested in the interpretation of the Book of Changes (Yijing 易經). Basing on this divination classic that is deeply influenced by Daoist thinking, Zhou Dunyi wrote his short "Explanation of the Diagram of Highest Motion" Taiji Tu Shuo (or Taijitu Shuo or Taiji tushuo) 太極圖說 and traced back all existing phenomena like seasons, the Five Elements, the active and inactive principles yin 陰 and yang 陽, and even the highest extreme, to be born out of a deep silence and motionlessness (wuji 無極). More important for Confucian thinking is his book "Comprehensive (Explanations) of the Book of Changes" (Yitong 易通, also called "Comprehensive Book" Tongshu 通書). Motionlessness being the source of everything, it is also the basis for acheiving sincerity (cheng 誠) which is the condition of becoming a perfect man or a saint (shengren 聖人). Sincerity, although being non-acting (wuwei 無為), is determining good (shan 善) or bad (e 惡). Virtue (de 德) is expressed as love or humanity (ai 愛, ren 仁), properness or righteousness (yi 宜, yi 義), order or ritus (li 理, li 禮), comprehending or knowing (tong 通, zhi 智), keeping or trusting (shou 守, xin 信). With the luminant principle yang, Heaven creates the beings and gives them a natural sense for human relationship, by the dark principle yin, Heaven accomplishes all beings, giving them righteousness. Heaven directly influences man, and the holy rulers as representatives educated their subject by humanity and righteousness, by rites (li 禮) to bring order (li 理) to people, and by music (yue 樂) to bring harmony (he 和) to the empire.
Zhang Zai 張載 (1020-1077) further developed the metaphysical background for the Confucian revival. He concentrated on the Book of Changes (Yijing 易經) and the Doctrine of the Mean Zhongyong 中庸. In his book "Correcting the Ignorant" Zhengmeng 正蒙, Zhang Zai postulated that the basic elementary component of the universe and all beings is odem or breath (qi 氣) which he called "Great Emptiness" (taixu 太虛) - that is in fact not empty, but is a substance to give shape to all things, from lowest to highest density. All phenomena within the universe are made from the Great Emptiness, only with different densities. The Great Emptiness bears the potential for movement and for a good and virtuous character, and every being possesses these potentials. "Western Inscriptions" Ximing 西銘 is another theoretical work of Zhang Zai, by that he stresses the unity of Heaven (Tian 天), Earth (Di 地) and all beings. All people are brothers and sisters because everybody is being born by Heaven. The ruler is the Son of Heaven, and the sage man possesses the right virtue produced by Heaven. The human nature also finds its source in Heaven and is therefore equally good in every man. The different character of people is expressed by the "quality of his/her substantiation" (qizhi 氣質), and even a bad substantiation can be led back to its good origin by proper education and self-control.
The numerologist Shao Yong 邵雍 (1011-1077) tried to explain the universal metaphysics with Daoist number speculations based on the Yijing 易經 "Book of Changes". All different beings in the universe, he states in his book Huangji jingshi 皇極經世, had their source in the "Ultimate Extreme" (taiji 太極), which is nothing else than Heaven. He discriminates between the Anterior Heaven (xiantian 先天), consisting of sun, moon, stars and the elements on earth, and the Posterior Heaven (houtian 後天), which was responsible for the universal coherence according to the Five Agents. If the moving character and the silent character of the elements is mixed up in a right way, the universal way is properly founded. The beings are created by a division of one into two, two into four and four into eight, a relation reflected in the Eight Hexagrams in the Book of Changes. Everything is born by the Highest Extreme, the center, heart or mind (xin 心) of the universe. The nature of every man and every being is therefore the same. Concerning the life cycle of history and dynasties, Shao Yong speculates that there exist four different stages, like there are four different qualities in the kind of rule and exert the Heavenly Mandate. Unfortunately, he does not create a scenario for the future.
The brothers Cheng Hao 程顥 (1032-1085) and Cheng Yi 程頤 (1033-1107; also called Master Yichuan 伊川先生) further developed these Proto-Neo-Confucian thoughts by getting rid of the Daoist influence in the cosmological theories. They concentrated on explaining and commenting important Confucian Classics like the Mengzi 孟子, the Analects Lunyu 論語, the Great Learning Daxue 大學 and the Doctrine of the Mean Zhongyong 中庸. The never changing base of the universe is the universal order (li 理). It is this order that causes everything to come into being by providing it with breath (qi 氣) that is ranging somewhere between a positive (yang 陽) and a negative side (yin 陰). Everything can be traced back to the universal order and can not be without it. Each person depends on it, each social relation and every personal character is determined by the universal order. Human nature (xing 性) should be good because it is given by the universal order. But the transformation into a being with the help of breath (qi 氣) can make a man either good or bad. But even bad character is an expression of the human ability (cai 才). To become a good person, one has to keep away from extremes and to follow a middle path. The good man has to observe the Heavenly path of universal order.
The greatest person of Neo-Confucianism is Zhu Xi 朱熹 (1130-1200), also called "Master Zhu" (Zhuzi 朱子). Because Neo-Confucian philosophers laid stress on an existing single-source of all universal phenomena, the universal order (li 理), Neo-Confucianism is called in Chinese the "Teachings of the Order" (Lixue 理學). Zhu Xi's teachings are the essence of the former philosophers and became orthodox under the Yuan dynasty. Zhu Xi explained that the unique source of the whole universe is the Heavenly Order (Tianli 天理), also called the Highest Extreme (Taiji 太極). This order and the universal breath (qi 氣) of dense or scattered matter are able to give shape to every beings. There does not exist Order without the shaping Breath, and no Breath without the Order. Every being has the same amount and character of Order, but every being is characterized by a different amount and character of Breath, thus making different elements, different beings, appearances and distinguishable people with different character, good or bad. Therefore, everybody seems to have a different order or character, what is in fact only the same order: One basis, different shapes (li yi fen shu 理一分殊), or with Zhu Xi's words, "taking water out of a river with a bowl or a bucket, you obtain different measures of water", but it is still water, only in different amounts and in a different environment. The human nature is determined by the environment, like "a pearl lying in water or in mud". But while the human nature is good in every man, the passions can be good or bad. Human nature is the universal order in the heart of man, that can be influenced by the environment.
Zhu Xi is the most important person of Confucianism after Confucius and Mengzi. He has not only been an important commentator of the classical and canonical texts, but his interpretations are undertaken as an explanation of the whole corpus of classical texts. His interpretations have been the orthodox exegesis of Confucian texts until the end of the Chinese empire. Secondly, Zhu Xi has accumulated the whole new cosmological and metaphysical interpretations of the Song Dynasty and has incorporated them into a new school, later known to us as Neo-Confucianism.
Zhu Xi's disciples further developed the theories of the universal order. The most important are the Song scholar Zhang Shi 張栻 (1133-1180), and the Qing scholars Gu Yanwu 顧炎武 (1613-1682) and Wang Fuzhi 王夫之 (1619-1692).
The most famous collection of Zhu Xi's philosophy is the Zhuzi Yulei 朱子語類. But "Master Zhu" has written a large treasury of interpretations and exegeses of many different philosophical matters (e.g. the interpretation of the Yijing Hexagrams Yixue Qimeng 易學啟蒙). And, like most Chinese scholars, Zhu Xi also engaged in calligraphy and poetry.
Lu Jiuyuan 陸九淵 (1139-1191) hat a somewhat different approach to the metaphysical theories of Zhu Xi and his forerunners. Still equally to these people, Lu and his brothers saw the cosm as bound by one single constant, the universal order (li 理 or dao 道 "way"). This order reached down to the social division between upper and lower, as granted by nature. People following this order are rewareded, disobedient people are punished by Heaven. The old rulers and sage emperors recognized the patterns of this order in all natural phenomena. Or, as Lu Jiuyuan said, they enlighened their heart or mind (xin 心). The heart of man is therefore equal to the universal order, it is a reflection of the natural patterns. The heart of the sage man is naturally equal to the heart of a mean man. In this point, Lu contradicts Zhu Xi who taught that the will and temperament of man (qing 情, yu 欲) destroys this natural order in the human nature (xing 性). If Heaven is order and man only wishes, they cannot be equal, is the argument of Lu Jiuyuan. While Zhu Xi stresses that spirit or mind is an objective reality, a composition of universal order and breath or matter, Lu Jiuyuan sees the spirit as dependent of sensual perception. Lu's philosophical school was the "School of the Mind" (Xinxue 心學 ). There came up severe struggles between the disciples of Zhu Xi and that of Lu Jiuyuan, but Zhu Xi's school had lost its strength and was overtopped by the great Ming philosopher Wang Shouren 王守仁 (Wang Yangming 王陽明), a representative of the Philosophy of the Mind.