Xu refers to a state of the cosmos or a state of mind. Basically, it has two different

meanings. The first refers to the origin of the universe, indicating that everything

originates from xu. Different ancient thinkers have different interpretations of

this notion: Some take xu as being devoid of anything; others believe it is the

state of existence of qi (气). Because qi is invisible and formless, it is said to be

empty, but not a vacuum totally devoid of anything. The second meaning of xu

refers to a state of mind that is peaceful, not preoccupied or simply free of any

preconceptions.