The Great Learning (大學, Dà Xué) is the first of the Four books which were selected by Zhu Xi in the Song Dynasty as a foundational introduction to Confucianism. It was originally one chapter in Li Ji (the Classic of Rites).
The book consists of a short main text, attributed to Confucius and nine commentaries chapters by Zhengzi, one of Confucius' disciples. It's importance is illustrated by Zhengzi's foreward that this is the gateway of learning.
Some of the terms within the text form an important part of both classical and modern Chinese political discourse. For example, the concept of world peace has been the stated goal of Chinese statecraft from the Zhou dynasty to the Kuomintang to the Communist Party of China. Another term used in the text qing-ming which Legge translates as renovating the people is the name of the People First Party, one of the major parties in the Republic of China on Taiwan.
The main text reads
Government, self cultivation and investigation of things are linked. It links together invididual action in the form of self-cultivation with higher goals such as ultimate world peace as well as linking together the spiritual and the material. In edition, by defining the path of learning (dao) in governmental and social terms, the Great Learning both links the spiritual with the practical, and creates a vision of dao that is radically different than that presented by daoism. In particular, the Great Learning sets Confucianism as being this-worldly rather than other-worldly. Finally, the Great Learning also creates a conservative politics discourse. Instead of basing its authority on an external deity, the Great Learning bases its authority on the practices of ancient kings.
The text also sets up a number of controversies that have underlain Chinese philosophy and political thinking. For example, one major controversy has been to define exactly the investigation of things. What things are to be investigated and how has been one of the crucial issues of Chinese philosophy.