The separation of an object’s hardness from its whiteness is a proposition advanced by Gongsunlongzi（320？-250 BC）. Looking at a hard and white stone, one can only see its whiteness but not its hardness; while touching the stone with one’s hand, one can only feel its hardness but not that it is white. Hardness and whiteness are separate. They do not manifest themselves at the same time: thus, a white stone that is hard cannot be called a hard and white stone. Gongsunlongzi used this example to express his understanding of the properties of things. These properties are independent of each other and cannot simultaneously be joined in the same thing.

Looking at it, one cannot see the hardness of the stone but only the whiteness, so it has no hardness. Touching it, one cannot feel the whiteness but only the hardness, so it has no whiteness. （Gongsunlongzi）