"Thirty spokes

meet in the hub.

Where the wheel isn't

is where it's useful.


Hollowed out, 

clay makes a pot.

Where the pot's not

is where it's useful.


Cut doors and windows

to make a room.

Where the room isn't,

there's room for you.


So the profit in what is

is in the use of what isn't."


— Ursula K. Le Guin, 

Tao Te Ching (Book One, Chapter 11)