磨砖成镜

Explanation: The brick and stone ground into the mirror. Metaphor of things can not be successful. 　　Usage: Supplemental; for the predicate; metaphor of things can not be successful 　　Source: Song, Buddhism, Taoism original "Master Hui Neng Jing Chuan Deng recorded": "One said: 'into the mirror grinding brick Qide evil?' The master said: 'Buddhist meditation Qide for evil?'" Thesaurus:  work fruitlessly, Sand to make rice cooking, For mirror grinding brick