Abstract
The central issue in the fraternal quarrel of the Joo period (1652-1655) is whether Saigin's thought deviated toward solipsism. At present this problem has not been sufficiently explored. Here I would like to examine the controversy on the basis of a document Saigin appears to have written earlier, namely the Fumonbonsho. There are insufficent materials upon which to base a comparison with Saigin's later thought, but it does seem that the quarrel had a serious impact. For this reason, the Fumonbonsho is an important source, and valuable for the development of Shinshu doctrine.
