《管子·形势解》
所以按常规办事就治，不按常规办事就乱，天从来不曾改变它的常规，因而总是处于 治 的状态。所以说： 天不变其常。 
故用常者治，失常者乱。天未尝变，其所以治也。故曰： 天不变其常。 
Therefore, doing things according to the rules is governing, and doing things against the rules is chaos. Heaven has never changed its rules, so it is always in a state of governance. Therefore, it is said: "Heaven does not change its normal behavior."