The origin of the colored belts, as well as the significance of the particular colors, is shrouded in mystery and may be permanently lost to history. While Jigero Kano left no documented reason for the various colors he used, he did believe that, if someone achieved a stage higher than tenth dan, then "one transcends such things as colours [sic] and grades and therefore returns to a white belt, thereby completing the full circle of Judo, as of life." The Kodokan decided the belt worn by such a person should be about twice as wide as the ordinary white belt to prevent any novices from mistaking the significance. Kano is the only person the Kodokan ever awarded twelfth dan, or shihan. Therefore, Kano's belt would be a double wide white belt.
As to the white belt being selected as the first belt, the Japanese people have considered white as symbolic of cleanliness and sacredness since ancient times. Therefore, it symbolizes the innocence and virtue of beginners. The white belt may also be related cotton being used to make the Judo uniform. After frequent washing, the natural cotton material tends to turn white.
As to the color belts, the adoption of court ranks in earliest records of the Japanese imperial sovereignty, the colored caps that denoted their rank, and strong regulations regarding rank relationships during these periods may have influenced Kano to adopt colored belts.