《管子·霸言》
如果天下有两个天子，天下就不能治理；一国而有两君，一国就不能治理；一家而有两父，一家就不能治理。
使天下两天子，天下不可理也：一国而两君，一国不可理也；一家而两父，一家不可理也。
If there are two emperors under heaven, the world cannot be governed; if there are two rulers in a country, the country cannot be governed; if there are two fathers in a family, the family cannot be governed.