From a developmental viewpoint the author of this article traces Ch'eng Hao's 程顥（alias 明道 , 1032-1085）theory of human nature and mind through his original Confucianism , his conversion to Buddhism and Taoism , and final embrace of Confucianism . He then reviews Ch'eng I's 程頤（alias 伊川 , 1033-1107）theory as developed from Ch'eng Hao's concept . A declared Confucianist from his late twenties on , Ch'eng Hao failed to conceal the influence of Buddhism and Taoism on his diction and mode of thought . As he reached maturity his concept of the mind （心） became an objectification and a moralization of the "everyday mind" （平常心） of Zen Buddhism . In addition , he equated human nature （性） with physical nature （氣質之性） so as to objectify as well as to resolve the problem of evil in human nature . During his early years Ch'eng I already confined human nature in moral categories , and described the mind as the knowing and moral behaving subject . Later he developed the twofold view of "ultimate nature" （極本窮源之性） and "existent nature" （生之謂性）. He also maintained that a person's capacity （his wisdom or foolishness） is determined by the clarity or turbidity of the vital force （氣之清濁） , while the goodness of human nature is actualized by , but not founded upon , one's capacity . As to the concept of the mind , Ch'eng I developed the idea of the mind substance （心體） , a state of mind before consciousness , by means of discussing the problem of "equilibrium and harmony"（中和）. The mind substance , equivalent to the knowing subject , is , however , the "human nature in concreteness"（性之有形者）, which may therefore be "the great foundation of the world"（天下之大本）. In line with his view of the mind substance as a state of mind before consciousness , Ch'eng I emphasized the importance of inner cultivation （涵養） or sincerity （敬） in moral cultivation .