无师自通 Master without a teacher
Explanation
指没有老师的传授就能通晓，形容人学习能力强，对某事有天赋，或者形容事物的原理或道理很容易理解。
Means to understand something without being taught by a teacher. Describes someone with a strong learning ability, a talent for something, or the easy understanding of principles or reasons.
Origin Story
从前，在江南水乡有一个叫小莲的女孩，她从小就对绘画充满了兴趣。她经常偷偷跑到村里的书画店里，观察着店里的画师们作画。小莲看得津津有味，有时还会自己动手练习。时间久了，她居然画得越来越好，甚至超过了店里的画师。大家都说小莲是无师自通，真是个绘画天才。小莲后来成为了远近闻名的画家，她的画作被人们争相收藏。
Once upon a time, there was a girl named Xiaolian who lived in a water village in southern China. She had a passion for painting since she was a little girl. She often snuck into the village's art store and watched the artists paint. Xiaolian watched with fascination, and sometimes she would try to paint herself. Over time, she became better and better at painting, even surpassing the store's artists. Everyone said Xiaolian was a natural, a true painting genius. Later, Xiaolian became a famous painter whose paintings were sought after by people.
Usage
形容一个人学习能力强，不用老师教就能学得很好，或者形容事物容易理解。
To describe someone who learns quickly and can learn well without a teacher, or something that is easy to understand.
Examples
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他从小就表现出很高的音乐天赋，真是无师自通。
ta cong xiao jiu biao xian chu hen gao de yin le tian fu, zhen shi wu shi zi tong.
He has shown a high musical talent since he was a child, he is a natural.
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我弟弟对电脑很感兴趣，在没有老师的情况下，他就能自学编程，真是无师自通
wo di di dui dian nao hen gan xing qu, zai mei you lao shi de qing kuang xia, ta jiu neng zi xue bian cheng, zhen shi wu shi zi tong
My younger brother is very interested in computers and can learn programming without a teacher, he is a natural