The "dokusan" practice in Rinzai Zen is a crucial aspect of the tradition, and it is often considered to be the heart of Rinzai Zen practice. Dokusan, which means "private interview" or "face-to-face encounter," is a one-on-one meeting between a Zen master and a student. During dokusan, the student presents their understanding and progress in their Zen practice, and the master offers guidance and instruction.

In Rinzai Zen, dokusan is considered to be an essential means of transmission of the teachings from the master to the student. It is believed that the true understanding of Zen cannot be conveyed through words or scriptures, but only through direct experience and personal interaction with a master. Dokusan provides a unique opportunity for the student to receive personalized guidance and instruction from the master, which is tailored to their individual needs and progress.

The format of dokusan is highly structured and ritualized, with specific etiquette and procedures to be followed. The student typically bows and enters the dokusan room, where the master is seated in a designated spot. The student then offers a brief statement or question to the master, which serves as a starting point for the interaction. The master may then ask further questions or give specific instructions for the student to contemplate or practice.

The purpose of dokusan is not to seek answers or solutions from the master, but rather to deepen the student's understanding and realization of their own true nature. The master may use various techniques, such as koans (paradoxical statements or questions), to challenge the student's thinking and break through their conceptual understanding. The goal of dokusan is for the student to experience a moment of enlightenment or awakening, which can then be integrated into their daily life and practice.

Hakuin Ekaku, the reviver of Rinzai Zen, is known for his strict and intense dokusan practice. He emphasized the importance of dokusan as the primary means of transmission in Rinzai Zen and believed that it was the most effective way to awaken students to their true nature. He also encouraged his students to engage in dokusan frequently, sometimes even multiple times a day, to deepen their understanding and progress in their practice.

In conclusion, dokusan is a crucial practice in Rinzai Zen, and it serves as a direct and personal means of transmission of the teachings from the master to the student. Through this intimate and intense practice, students can deepen their understanding and experience moments of awakening, leading to a transformation of their entire being.