Yanagi's book "The Unknown Craftsman" has become an influential work since its first release in English in 1972. In it, he examines the Japanese way of viewing and appreciating art and beauty in everyday crafts. At the same time, however, – and by his own admission – his theory was not simply a craft movement based on aesthetics, but "a spiritual movement" in which craftsmen should work according to ethical and religious ideals, if beauty was to be achieved. In this respect, it may be argued that he chose to express his vision of "spirituality" through the medium of folk crafts and was, as a result, concerned with "how" folk crafts were made, rather than with these crafts as objects in themselves. Provided that they were made according to a certain set of rules laid down by himself, they would naturally accord with his concept of "beauty".