Fortress / City
Cheng (城) is a city with walls surrounding it. The Chinese character for cheng originally referred to inner and outer city walls built of earth, with military defense and flood control functions. Usually, it was surrounded by a moat. In ancient times, the state capital of a monarch, the fief of a prince, and a manor estate granted by a monarch to a minister or a senior official all had a walled settlement as the center, hence the name cheng. The Chinese character for cheng is pronounced the same way as another character meaning accommodating. Here, cheng means having the capacity to accommodate people. The primary function of a cheng is to protect its residents. This is a concrete manifestation of the political notion that people are the foundation of the state.
A fortress / city is a facility used to defend the people inside. (Mozi)
A fortress / city is for accommodating people. (Xu Shen: Explanation of Script and Elucidation of Characters)
A fortress / city is built to protect people. (Guliang’s Commentary on The Spring and Autumn Annals)