Zheng Meng 正蒙 (Correct Discipline for Beginners or Rectify the Obscure or Correct the Ignorant) is considered the most important work of the philosopher Zhang Zai. There have been many Chinese commentaries, of which the best known is Zhangzi Zheng Meng Zhu (Commentary on Zhangzi’s Correct Discipline for Youth) by Wang Fuzhi (1619-1692), this was reprinted in 1975.
In this text Zhang Zai argues that the basic elementary component of the universe and all beings is qi 氣, which he called taixu 太虛 - "Great Emptiness". Tai xu is the source of all phenomena within the universe and also the potential for phenomena. Zheng Meng was the first philosopher to argue that qi is the essence of the Way, and he systematically described the formation and transformation of all things in terms of qi.
Zhang Zai (1020-1077) was born in Henan Province, but lived in Hengqi, Shaanzxi Province for most of his life. He is called Hengqu for this reason and his name is also styled Zihou. He lived in the Song Dynasty and was a well known confucian scholar.
Zhang Zai wrote extensively on qi. He studied Daoism and Buddhism in early life but focused his studies on Zhongyong (Doctrine of the Mean) by age 21. After that he studied Confucianism and was a scholar of the Yi Jing. He was a wide spoken critic of Buddhism. He was the first philosopher to organize the concept of qi and its central role in the universe as it has been seen since.
Huang, Siu-chi, trans, Essentials of Neoconfuciansim: Eight Major Philosophers of the Song and Ming Periods. Westport: Greenwood Press, 1999.
Zhang Zai, Zhang Zai ji, Beijing, Zhonghua shuju, 1978.
This is a complete collection (and the best edition) of Zang Zai's work, that contains Zheng meng (Rectifying the obscure), Jingxue li ku (Treasury of li in the Confucian classics), Hengqu Yishuo (Zhang Zai's discourse on the Yijing).