Where did the idiom "become a master" originally come from? What's the explanation?

Banmen Nongaxe

Words: Banmen Nongaxe

Pronunciation: bān mén nòng fǔ

Definition: Dancing with the ax in front of Luban Gate. It is a metaphor for showing off one's skills in front of experts and not overestimating one's abilities.

Source: Tang Dynasty Liu Zongyuan's "Preface to the Singing Poems of Wang's Brothers": "Using the ax at the gate of Ban and Ying is a strong Yaner." Song Dynasty Ouyang Xiu's "Book with Mei Shengyu": "Yesterday is true "Ding, there are seven or eight poems. I will record them now. It's ridiculous to play with the ax in the class."

I heard that Sister Tingting is very knowledgeable, how dare I talk nonsense with him. (Chapter 52 of Li Ruzhen's "Flowers in the Mirror" of the Qing Dynasty)

A pile of soil by the quarrying river, Li Bai's name will last forever;

A poem comes and goes, Luban gets a big ax in front of the gate.

This is "Inscription on Li Bai's Tomb" by a poet from the Ming Dynasty. Li Bai is a world-famous poet of the Tang Dynasty, and his fame will be passed down through the ages after his death. How many literati passed by Li Bai's tomb wanted to stop for a while and recite poems to express their inner feelings. And their behavior can only be arty, "Lu Ban is doing everything in front of the door", which is too overestimating their own capabilities.

Lu Ban was a native of Lu during the Warring States Period. He is a master who is good at making exquisite utensils. People call him "Qiaoren" and the people have always regarded him as the ancestor of carpenters. Anyone who dares to show off his ax skills in front of Lu Ban's gate, that is, wants to show off his skills in front of big experts, is such an immodest and ridiculous behavior, it is called "making a big ax in front of Lu Ban's gate", or "making an ax in front of Lu Ban's gate" for short. . This is similar to the saying that "Guan Gong plays with a big sword in front of him".

In fact, the idiom "everyone works with an axe" had its prototype as early as the Tang Dynasty. Literary scholar Liu Zongyuan has this sentence in a preface: "Use an ax at the gate of Ban Ying, Si Yan'er!" This means that the use of an ax is shown in front of the gate of Lu Ban and Ying people (who are also expert axes). He's too thick-skinned for his ability.

This idiom is sometimes used as a self-effacing word to express that one does not dare to show off one's little skills in front of experts.

English: show off one's skill or knowledge before an expert