teachers, such as Harada Daiun Sogaku and Shunryū Suzuki, have criticized Japanese Zen as being a formalized system of empty rituals in which very few Zen practitioners ever actually attained realization. They assert that almost all Japanese temples have become family businesses handed down from father to son, and the Zen priest's function has largely been reduced to officiating at funerals, a practice sardonically referred to in Japan as . For example, the Sōtō school published statistics stating that 80 percent of laity visited temples only for reasons having to do with funerals and death. Teachings Buddha-nature and sunyata Mahayana Buddhism teaches śūnyatā, "emptiness", which is also emphasized by Zen. But another important doctrine is the buddha-nature, the idea that all human beings have the possibility to awaken. All living creatures are supposed to have the Buddha-nature, but don't realize this as long as they are not awakened. The doctrine of an essential nature can easily lead to the idea that there is an unchanging essential nature or reality behind the changing world of appearances. The difference and reconciliation of these two doctrines is the central theme of the Laṅkāvatāra Sūtra. Kensho: seeing one's true nature The primary goal of Rinzai Zen is kensho, seeing one's true nature, and mujodo no taigen, expression of this insight in daily life. Seeing one's true nature means seeing that there is no essential 'I' or 'self', that our true nature is empty. Expression in daily life means that this is not only a contemplative insight, but that our lives are expressions of this selfless existence. Zen meditation Zen emphasizes zazen, meditation c.q. dhyana in a sitting 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 shiryō and hi shiryō. According to Zhu, the two terms negate two different cognitive functions both called manas in Yogacara, namely "intentionality" or self-centered thinking, and "discriminative thinking" (vikalpa). The usage of two different terms for "non-thinking" points to a