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 altar where one prays to and communicates with deceased family members. As such, reciting liturgy in Zen can be seen as a means to connect with the Bodhisattvas of the past. Liturgy is often used during funerals, memorials, and other special events as means to invoke the aid of supernatural powers. Chanting usually centers on major bodhisattvas like Avalokiteśvara (see Guanyin) and Manjushri. According to Mahayana Buddhism, bodhisattvas are beings who have taken vows to remain in saṃsāra to help all beings achieve liberation from it. Since the Zen practitioner's aim is to walk the bodhisattva path, chanting can be