Gibon Sengai (1750-1837) was one of the great Zen masters in Edo period. He was famous and popular as a Zen master who produced ink-drawings and calligraphies satirically and humorously.
Against such a Sengai's image, this thesis aims to describe new Sengai's image as an academic priest through the analysis of many of his books nobody has studied thoroughly yet. Particularly, I chose one of his ink-drawings "□△○" as a material for this study, and pursued the profundity of his Zen thought. In a word his thought can be found in the word of Eisai who was the first patriarch of Japanese Rinzai's Zen
that is "How great a mind is!" Namely he didn't grasp the essence of the world in things that are relative and limited, but grasped the great essence in "mind."