Dhyāna in Buddhism "silent illumination." This became the source of some differences in practice between the Línjì and Cáodòng schools. A kōan, literally "public case", is a story or dialogue, describing an interaction between a Zen master and a student. These anecdotes give a demonstration of the master's insight. Koans emphasize the non-conceptional insight that the Buddhist teachings are pointing to. Koans can be used to provoke the "great doubt", and test a student's progress in Zen practice. Kōan-inquiry may be practiced during zazen (sitting meditation), kinhin (walking meditation), and throughout all the activities of daily life. Kōan practice is particularly emphasized by
Zen Yasutani and the Sanbo Kyodan. This picture has been challenged, and complemented, since the 1970s by modern scientific research on Zen. Modern scientific research on the history of Zen discerns three main narratives concerning Zen, its history and its teachings: Traditional Zen Narrative (TZN), Buddhist Modernism (BM), Historical and Cultural Criticism (HCC). An external narrative is Nondualism, which claims Zen to be a token of a universal nondualist essence of religions. The history of Chán in China can be divided into several periods. Zen as we know it today is the result of a long history, with many changes and