How can grinding bricks become a

（道一传）
开元中有沙门道一，在衡岳山常习坐禅。师知是法器，往问曰：“大德坐禅图甚么？”一曰：“图作佛。”师乃取一砖，于彼庵前石上磨。 一曰：“磨作甚么？”师曰：“磨作镜。”一曰：“磨砖岂得成镜邪？”师曰：“磨砖既不成镜，坐禅岂得作佛？”……

小和尚“道一”，在衡岳山中打坐学习佛法，师傅知道他是个可以培养的人生，问“道一”：你为什么打坐。
“道一”回答：想成为佛
师傅于是取了一砖，在他面前磨砖。
“道一”问：磨砖做什么
师傅回答：做镜子
“道一”说：磨砖怎么能成为镜子
师傅回答：磨砖不能成为镜子，打坐怎么能成为佛

The young monk "Tao Yi", meditated in Hengyue Mountain to learn Buddhism. The master knew that he was a life that could be cultivated, and asked "Tao Yi": Why do you meditate.
"Tao Yi" said: I want to be a Buddha
The master took a brick and polished it in front of him.
"Tao Yi" asks: What does grinding brick do?
The master answered: make a mirror
"Tao Yi" said: How can grinding bricks become a mirror
The master say: Grinding bricks cannot be a mirror, how can meditating become a Buddha?