城池改造，井的位置不变。井即水井，也指古代社会的组织单位，八家为一井。人类的生存离不开水，聚集之地多有水井。而井为水脉所限，不能轻易变更，故无论人类的居所如何改造、迁徙，水源都是不动的参照点。其中隐含的智慧是：无论诸多事项如何变动，人类生存所必需的基本要素要保持稳定。

　　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.

　　引例

　　改邑不改井，无丧无得。往来井井。（《周易·井卦》）（城邑常有改易，而水井不能随意迁徙，井水也不会因人们的汲用而枯竭或满盈。人们每天往来汲水，都能得其所用。）

　　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)