Zhu Xi was one of many critics who argued that government schools did not sufficiently encourage personal cultivation of the self and molded students into officials who cared only for profit and salary. Not all social and political philosophers in the Song period blamed the examination system as the root of the problem (but merely as a method of recruitment and selection), emphasizing instead the gentry's failure to take responsibility in society as the cultural elite. Zhu Xi also laid emphasis on the Four Books, a series of Confucian classics that would become the official introduction of education for all Confucian students, yet were initially discarded by his contemporaries. After his death, his commentary on the Four Books found appeal amongst scholar-officials and in 1241 his writings were adopted as mandatory readings for examination candidates with the support of Emperor Lizong (r. 1224–1264).