Rather these kuji and juji originated strictly within Japanese Buddhism is unlikely as Jodo Shinshu is, like many things in Japanese theology, influenced by Taoism. And it is also safe to assume that both Kakuban and Shinran would have been familiar with the various Taoist kuji and juji formulas. Rather or not their kuji and juji formulas are Japanese versions of Taoist formulas may never be known. However, what is clear is that they represent the earliest known use of the kuji and juji in Japanese esoteric Buddhism . (Waterhouse, 1996)