THE USES OF NOT
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.
--Lao Tzu
from Ursula K. Le Guin's
Lao Tzu: Tao Te Ching:
A Book About the Way and the Power of the Way