 The semantics of "po" "white soul" probably originated with "lunar whiteness".Zhou bronze inscriptions commonly recorded lunar phases with the terms "jishengpo" "after the brightness has grown" and "jisipo" "after the brightness has died", which Schuessler explains as "second quarter of the lunar month" and "last quarter of the lunar month".Chinese scholars have variously interpreted these two terms as lunar quarters or fixed days, and (Shaughnessy 1992