Tao Te Ching, Lao Tz, Chapter 11
Thirty spokes share the wheel’s hub;
It is the center hole that makes it useful.
Shape clay into a vessel;
It is the space within that makes it useful.
Cut doors and windows for a room;
It is the holes which make it useful.
Therefore profit comes from what is there;
Usefulness from what is not there.
USE AND MAINTENANCE:
Oven : avoid cooking above 150 Celsius
Safe for food and drink use!