The characters literally combine to tell a story: “iron pestle (铁杵) is ground (磨) into becoming (成) a needle (针).” The meaning is derived directly from this powerful visual metaphor.
The soul of this idiom lies in a famous, almost legendary, story about Li Bai (李白), one of China's most celebrated poets from the Tang Dynasty. As a young boy, Li Bai was brilliant but disliked the drudgery of studying and one day decided to skip school. While wandering, he came across an old woman by a river, patiently grinding a thick iron pestle on a whetstone. Curious, he asked her, “Grandma, what are you doing?” She replied without stopping, “I'm grinding this iron pestle into a sewing needle.” Li Bai laughed in disbelief. “But that's impossible! It will take forever!” The old woman calmly answered, “As long as I keep at it, I will succeed one day.” (只要功夫深,铁杵磨成针 - Zhǐyào gōngfu shēn, tiěchǔ mó chéng zhēn). This encounter was a profound lesson for the young Li Bai. He understood the power of diligence, returned to his studies with renewed vigor, and eventually became a literary giant. This story is taught to virtually every child in China, embedding the values of perseverance, patience, and grit from a young age. Comparison to a Western Concept: A similar Western proverb is “Rome wasn't built in a day.” Both idioms teach patience for long-term goals. However, the Chinese idiom is more visceral and personal. “Rome wasn't built in a day” suggests a large-scale project requiring collective time. 铁杵磨成针 focuses on an individual's seemingly futile, yet ultimately triumphant, struggle against impossible odds. The imagery highlights the transformative power of one person's will, turning something coarse and massive into something fine and intricate.
This idiom is alive and well in modern China. It's a go-to phrase for motivation and encouragement.
Its connotation is overwhelmingly positive and inspirational. It can be used formally in a speech or informally between friends. It's a timeless piece of wisdom that everyone understands.