Hui-neng's definition of sitting meditation; the middle way as the avoiding of the 'deadends' of existence and non-existence; the Greek philosopher Pyrrho as an example of a similar attitude; Hui-ko asks Bodhidharma to 'set his mind at rest'; the infinity of things; emptiness as the unfindability of things; to question 'what is this' is the practice of such emptiness that neither affirms nor denies anything.