《易传·系辞传下·第十二章》
乾象是天下最刚健的，表现为刚健之处，是在于恒久而平易，且无私意，故可以明照出天下危险的事情。
夫乾，天下之至健也，德行恒易以知险。
The image of Qian is the most forceful in the world, its forcefulness is manifested in being constant and even, and selfless, so it can illuminate the dangerous things in the world.