Of the Mahayana shortcuts to enlightenment, the Zen traditions have, over time, gravitated toward two in particular. The Rinzai tradition has taken an interesting approach, one that might seem uncharacteristic at first. If the Dharma transmission that first propagated Zen, with its emphasis on nonverbal expression, is the true harbinger of the Zen practices, a tradition encouraging verbal exercises might seem incongruous. The koan practice is a verbal exercise designed to excise the rationalizing mind from the Buddha-mind. This leads to an experience of emptiness. Koans are not “solved.” The application of logical reasoning is unhelpful and unnecessary for koan study.

The three classic koan texts are the Blue Cliff Record, the Book of Equanimity, and the Gateless Gate.