In social structures, relationships that ‘could be’ are as important or more important than those that are already there. Ron Burt (2005, etc) refers to such ’empty spaces’ as “structural holes” – holes that provide opportunities for new relationships as well as access to new information and new resources. This notion is not new. Lao Tzu refers to such things in the Tao Te Ching as early as 200 BC:

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.

Tao Te Ching – Lao Tzu – A Comparative Study
(Available online at: http://www.wussu.com/laotzu/laotzu11.html)