"Thirty spokes meet in the hub. Where..." - Quote by Lao Tzu
Thirty spokes meet in the hub. Where a wheel isn't is where it's useful. Hollowed out, clay makes a pot. Where the pots 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.
An image illustrating the quote: "Thirty spokes meet in the hub. Where a wheel isn't is where it's useful. Hollow..."