《战国策·韩二·史疾为韩使楚》
现在盗贼公然横行却不能加以禁止，就因为各个官员不能胜任其职，这就叫做： 乌鸦不成其为乌鸦，喜鹊不成其为喜鹊啊！  
今盗贼公行，而弗能禁也，此乌不为乌，鹊不为鹊也。 
As for the thieves rampant now and not being prohibited, it is because the officials are not competent for their offices. This is what is called: "Crows cannot be crows, magpies cannot be magpies!"