In his Liusu t'an ching 六祖禪經, The Platform Sutra, Hui-neng 惠能 says that if one were to stay free from attachment to any mental or physical realms, and to think of neither good nor evil, that is, refrain from discriminating, neither thought nor mind will arise. This would be the true "sitting" of Ch'an. Here, "sitting", not limited to mere physical sitting, refers to a practice where the mind is not influenced, disturbed, or distracted, by anything coming up, whether internally or in the environment. If you were to experience your self-nature, this would be called "Ch'an" (Kensho in Zen). To see self-nature is to see one's own unmoving Buddha-nature, and is the most fundamental level of enlightenment. Without tso-ch'an in this sense, one cannot attain Ch'an. Hence tso-ch'an is the method, Ch'an the result. Since Ch'an is sudden enlightenment, when it occurs, it is simultaneous with tso-ch'an.

Hui-neng was critical of certain attitudes in practice which did not conform to his criteria of the true tso-ch'an which leads to Ch'an. These practices are referred to as "outer path" tso-ch'an because they are also found in other disciplines, for example, Taoism. A couple of anecdotes will illustrate some of these not-Ch'an attitudes in tso-ch'an.