Clay is molded to form a cup, But it is on its non-being that the utility of the cup depends. Doors and windows are cut out to make a room, But it is on its non-being that the utility of the room depends. Therefore turn being into advantage, and turn non-being into utility.
LaoziKnowing others is wisdom; Knowing the self is enlightenment; Mastering others requires force; Mastering the self needs strength.
Laozi