《淮南子·人间训》
静居时知道在做什么、行动时知道该去哪里、办事时知道所依原则、举动时知道来历缘由，达到这种境界的叫 道 。 道 ，置搁前头它不会低伏，放在后面它不会翘起，纳入窄处它不显壅塞，散布天下它不留空隙。
居知所为，行智所之，事智所秉，动智所由，谓之道。道者，置之前而不挚，错之后而不轩，内之寻常而不塞，布之天下而不窕。
When you are quiet, you know what you are doing; when you are acting, you know where to go; when you are doing things, you know the principles to follow; when you are acting, you know the origin and cause. This state of mind is called 道. 道, put it in front, it will not bow down; put it behind, it will not stand up; put it in a narrow place, it will not appear congested; spread it all over the world, it will not leave Gaps.