Two opposing properties or qualities that objects and human beings possess. The term has three different meanings. First, when describing natural or manmade objects, gang (刚) means hard and rou (柔) means soft. Second, when describing human qualities, gang means strong and determined, while rou means gentle and modest. Third, when describing a style of governance or law enforcement, gang means stern and rou means lenient. Gang and rou are one of the manifestations of yin and yang. Their mutual opposition and accommodation are the basic causes of change, and they must achieve a certain balance within any object or action. Too much of either is inappropriate and dangerous.

The laws governing the ways of heaven are yin and yang, those governing the ways of the earth are rou and gang, and those governing the ways of human society are benevolence and righteousness. (The Book of Changes)

Change occurs when gang and rou interact. (The Book of Changes)