The stillness of the mind of the sage is the mirror of heaven and earth, the looking glass of the myriad things. Mair 1994: 119-120) Many scholars of Chinese philosophy have analyzed the mirror metaphor for the xin "heart-mind".
Harold Oshima (1983: 75) explains that for a modern Westerner who regards a mirror as a commonplace looking-glass, this metaphor "appears quite pedestrian and unexciting" until one realizes that the ancient Chinese imagined mirrors "to possess broad and mysterious powers." For instance, a mirror can reveal and control demons.
"Certainly this mirror symbolized a powerful connection with the greater powers of the heavens and, as such, would have served admirably as a model for the [xin]." For the early Chinese, mirrors were not simply passive "reflectors" of information, they offered accurate and appropriate responses to whatever came before them.
From the left and right of the girdle [a son] should hang their articles for use—on the left side, the duster and handkerchief, the knife and whetstone, the small spike, and the metal speculum for getting fire from the sun [金燧]; on the right, the archer's thimble for the thumb and the armlet, the tube for writing instruments, the knife-case [or "needle-case" for a daughter-in-law], the larger spike, and the borer for getting fire from wood [木燧]. Legge 1885 27: 449, 450) Zheng Xuan's Liji commentary glosses musui as zuānhuǒ 鑽火 "produce fire by friction".
It is because the myriad things are unable to disturb his mind that he is still.