Liu Hsin and His Theory of the Beginning of the Schools
Liu Hsin's theory has been greatly elaborated by later scholars, especially by Chang Hsüeh-ch'eng (1738-1801) and the late Chang Ping-lin. In essence, it maintains that in the early Chou dynasty (1122?-256 B.C.), before the social institutions of that age disintegrated, there was "no separation between officers and teachers". In other words the officers of a certain department of the government were at the same time the transmitters of the branch of learning pertaining to that department. These officers, like the feudal lords of the day, held their posts on a hereditary basis. Hence there was then only "official learning" but no "private teaching". That is to say, nobody taught any branch of learning as a private individual. Any such teaching was carried on only by officers in their capacity as members of one or another department of the government.
According to this theory, however, when the Chou ruling house lost its power during the later centuries of the Chou dynasty, the officers of the governmental departments lost their former positions and scattered throughout the country. They then turned to the teaching of their special branches of knowledge in a private capacity. Thus they were then no longer "officers", but only private "teachers". And it was out of this separation between teachers and officers that the different schools arose.