Overstep the Mark of One's Authority

The Chinese idiom 越俎代庖 (yue4 zu3 dai4 pao2) literally means don't go into the kitchen to take over the role of cook. This idiom was first used by a sage called Xu You. According to the legend, Xu lived alone near Mount Qishan. He was as pure as the driven snow and consequently much loved by the locals.

One day, the monarch Tang Yao came to see Xu and, with the following seemingly wise words, indicated that he intended to offer his throne to the sage:

It is meaningless to light a candle after the sun comes out and it is ill-advised to water te field when it is raining. If such a wise and highly gifted man as you were prepared to take over my job our state will be better administered and will become more powerful and prosperous in the future.

Xu replied:

Your majesty is doing a good job running the state. It would be a mistake to replac your proven ability in administering the state with someone, such as me, who only has proven abilities in other areas. For even if the cook is not making the sacrificial meals, the official in charge of the sacrificial utensils should not go into the kitchen and take over the cook's job.

Ever since, the Chinese expression 越俎代庖 (yue4 zu3 dai4 pao2) has been used to describe the behaviour of someone who is trying to take over the role of another. In Chinese culture, such behaviour is inadvisable and is a sign of disrespect. So, next time someone tries to meddle in your affairs you'll know what to say - don't go into the kitchen and play cook. I have not been able to think of an equivalent English expression. It is similar to mind your own business, but this (I think) has a more general usage than 越俎代庖 (yue4 zu3 dai4 pao2).