The position on enlightenment supposedly taken by the ‘Southern School’ of Chinese Ch'an in the Northern–Southern Schools Controversy of the 8th century. This position is generally opposed to that of ‘gradual enlightenment’. Based on an extreme philosophical non-dualism that denies any inherent or substantial difference (though without positing an identity) between dyadic pairs such as practice and attainment, ignorance (avidyā) and wisdom, saṃsāra andnirvāṇa.and cause and effect, this position asserts that enlightenment comes suddenly, or more accurately instantaneously. This is so because the lack of difference between path and goal means that there is literally nowhere to go and nothing to attain; the goal is already in hand and needs only be known. In contrast, the gradualist position holds that one must go through a process, however short or long, to purify the mind and rectify conduct, thereby moving along a path toward the goal. The ‘subitists’ (see subitism), or those who held to the position of sudden enlightenment, criticized such a vision of Buddhist practice and attainment as philosophically untenable, since it artificially differentiated the paired terms given above. In the aftermath of the controversy, the language of sudden enlightenment became normative, and even though historically the Ch'an school in China and its derivatives in Japan.Korea.and Vietnam taught paths of practice, they were always careful to explain the efficacy of these practices in terms of the philosophy of sudden enlightenment.