This legend is about Li Bai (lǐ baí 李白), a great poet in Tang Dynasty (táng cháo 唐代). Li Bai was naughty and disliked study when he was a child. One day he saw an old woman grinding an iron rod on a big stone when he was playing by a river. Driven by curiosity, Li Bai came up and asked,
"What are you doing, granny?"
"Grinding an iron rod," said the old women without stopping grinding.
"Then what for?" he asked again.
"To make a sewing needle," was the answer.
"What?!" little Li Bai was puzzled, "you want to grind so big a rod into a needle?！It will take many years."
"This doesn't matter. As long as I persevere in doing so, there is nothing you cannot achieve in the world. Certainly I can make a needle from the rod." Deeply moved by what the old woman said, Li Bai took effort to study since then and finally became one of the greatest poets in China.

这是个关于中国唐代大诗人李白的传说。
李白小的时候非常调皮，不喜欢读书。 一天他在河边玩耍的时候看见一位老妇人拿着一根铁棒在大石头上磨。 李白非常好奇，问那个老妇人：
“你在干什么呀，老奶奶？”
老妇人边磨边说：“在磨铁棒。”
“磨这个干什么用啊？” 李白又问。
“做一根绣花针。” 老妇人回答。
“什么？！” 小李白听糊涂了。“你想把这么粗的铁棒磨成绣花针？！可是这要花好多年
啊！”
“这没有关系？只要我坚持下去，世上没有办不到的事，我一定能把铁棒磨成针的。”
老妇人的话深深打动了李白。从此，他认真刻苦地学习，最终成为了一名伟大的诗人。

只要工夫深，铁杵磨成针 (zhǐ yào gōng fū shēn,tiě chǔ mó chéng zhēn)
【翻译】So long as you have put a great deal of effort, you can grind an iron rod into a
            needle-Perseverance spells success.
【释义】比喻只要有决心，肯下功夫，多么难的事也能做成功。
【例句】“只要功夫深,铁杵磨成针",经过许多年的刻苦努力,他终于能说一口流利的汉语了。
【近义词】聚沙成塔、水滴石穿
【反义词】杯水车薪、半途而废