Japanese Zen expressions of this selfless existence. Zen emphasizes zazen, meditation c.q. dhyana in astting position. In Soto, the emphasis is on shikantaza, 'just sitting', while Rinzai also uses koans to train the mind. In alternation with zazen, there is walking meditation, "kinhin", in which one walks with full attention. To facilitate insight, a Zen teacher can assign a kōan. This is a short anecdote, which seems irrational, but contains subtle references to the Buddhist teachings. An example of a kōan is Joshu's 'Mu': "A monk asked: "Does a dog have buddha-nature?" Joshu responded: "Mu!"" Zen-meditation aims at "non-thinking," in Japanese "fu
Doctrinal background of Zen we conceive of is the result of the working of the five skandhas—results of perception, feeling, volition, and discrimination. The five skandhas together compose consciousness. The "things" we are conscious of are "mere concepts", not "Ding an sich". It took Chinese Buddhism several centuries to recognize that sunyata does not refer to "wu", "nothingness", nor does Buddhism postulate an undying soul. The influence of those various doctrinal and textual backgrounds is still discernible in Zen. Zen teachers still refer to Buddha-nature, but the Zen tradition also emphasizes that Buddha-nature "is" sunyata, the absence of an independent and substantial self. In