"Blue Mountains Walking" is a sculptural work from a series he made called bontei or tray gardens. It falls into a Japanese, and generally East Asian tradition of creating artworks that distill the natural world into abstract forms via trays. This includes bonsai (plants on trays) and bonseki/suiseki (stones on trays). The title Blue Mountains Walking is taken from a line in the opening of the Mountains and Waters Sutra (Sansuikyō 山水経) written by the Zen priest Dōgen in the 13th century. By writing that the "mountains are walking," Dōgen points out that even a mountain-the quintessential image of permanence and solidity-when seen from a certain perspective, can be understood to be fluid, ever-changing, and impermanent.