A weasel, on being caught by a man, wishing to escape impending death: "Pray," Said she, "Do spare me, for 'tis I who keep your house clear of troublesome mice." The man made answer: "If you did so for my sake, it would be a reason for thanking you, and I should have granted you the pardon you entreat. but, inasmuch as you do your best that you may enjoy the scraps which they would have gnawed, and devour the mice as well, don't think of placing your pretended services to my account;" And so saying, he put the wicked creature to death. 
Those persons ought to recognize this as applicable to themselves, whose object is private advantage, and who boast to the unthinking of an unreal merit. 