what is not…

Thirty spokes join the wheel nave
And make of void and form a pair,
And a wagon’s put to use.

Clay is thrown to shape a pot
And make of void and form a pair,
And a vessel’s put to use.

Door and window vent a home,
And make of void and form a pair,
And a home is put to use.

Thus the value of what is
Depends for use on what is not…

~ Lao Tzu