gǎi yì bú gǎi jǐng 改邑不改井
You Can Change a Town, But You Cannot Change the Wells.
You can change a town, but you should not relocate the wells. Wells, where drinking water comes from, also refer to the social units of ancient China, where eight households shared one well. Humans cannot live without water, so places where they gather mostly have wells. Underground water determines the location of wells which cannot be changed easily. No matter how people’s houses were moved and rebuilt, the wells were immovable landmarks. The meaning implied here is that however much things are reshaped, the basic needs of people’s livelihood stay the same.
The town can be changed, but the wells cannot be relocated. They neither dry up nor increase. People come and go every day, drawing water from the wells.(The Book of Changes)