Man macht Türen und Fenster,
damit das Haus werde;
In ihrem Nichts besteht des Hauses Werk.
Darum: Was ist, dient dem Besitz.
Was nicht ist, dient dem Werk
[Lao-Tse, Tao te king]
Cut doors and windows for a room;
It is the holes which make it useful.
Therefore benefit comes from what is there;
Usefulness from what is not there.