It is well known that Ch'ing-t'an (清談) had prevailed in the Wei-Chin (魏晋) periods. The oringin of Ch'ing-t'an, however, lies in the 'T'an-lun' (談論) that had been prevalent at the end of the Hou-Han (後漢) period (147-219).
A careful and detailed study of the contents of T'an-lun reveals that in it there are mainly two tendencies: the one is the tendency. to criticize contemporary men and politics on the basis of the moral and traditional standard; the other is the tendency to search for the essence of things with reason and freedom.
Even at the same period, that is, at the end of the Hou-Han period, the former treid prevailed first, and then the latter was derived from the former. These two tendencies their turns lived into the Wei-Chin periods and became Ch'ing-t'an, in which, however, more stress was laid on the tendency towards search for essence of things, and further combined with the Lao Chuang (老荘) thought.