From Han Yu’s yuan Dao 原道 (retracing the Dao) to Ouyang Xiu’s lun ben 论本 (discussing the root), the conflicts arising from Confucianists’ rejection of Buddhism were focused on one point, namely, the examination of zhongxin suo shou 中心所守 (something kept in mind). The attitude towards the distinction between mind and trace, and the proper approach to erase the gap between emptiness and being, as well as that between the expedient and the true, became the major concerns unavoidable for various thinkers to integrate the two teachings and to propel academic development. “To understand by mind” and “to blame for matter” were of crucial methodological significance for transcendence in both Confucianism and Buddhism. The arguments of Confucian scholars like Zhang Zai and the Cheng brothers on the identity of mind and trace and the unity of void and solid are mutually manifested. The same mind with the same principle means “mind is principle.” The “common axis of Confucianism and Buddhism” exists in the emphasis on mind beyond trace. The unification of mind and trace or the accordance of body and function has actually become the cardinal foundation for the possible mergence of the Three Teachings.