The following is, in my opinion, the best "chapter" in the Tao Te Ching, by Lao Tzu.
<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."