This paper explores a debate that took place in Japan in the early twentieth century over the comparability of hypnosis and Zen. The debate was among the first exchanges between psychology and Buddhism in Japan, and it cast doubt on previous assumptions that a clear boundary existed between the two fields. In the debate, we find that contemporaries readily incorporated ideas from psychology and Buddhism to reconstruct the experiences and concepts of hypnosis and Buddhist nothingness. The resulting new theories and techniques of nothingness were fruits of a fairly fluid boundary between the two fields. The debate, moreover, reveals that psychology tried to address the challenges and possibilities posed by religious introspective meditation and intuitive experiences in a positive way. In the end, however, psychology no longer regarded them as viable experimental or psychotherapeutic tools but merely as particular subjective experiences to be investigated and explained.
Keywords: Buddhist psychology; Hypnosis; Shaku Sōyen; Tomokichi Fukurai; Yūjirō Motora; Zen; meditation; modern occultism; nothingness; science and religion.