who maintain the Tao do not want to be full

"Chapter 15

In ancient times, those who were well educated were in communion with heaven, and were subtle, profound, mysterious and penetratingly wise.
Their depth was unfathomable.
Because of this, they appeared reluctant, hesitant, like one wading across a stream in winter;
Wary, as if there were dangers on all four sides;
Solemn, as if a guest;
Yielding, like ice on the verge of melting;
Pure, like uncarved wood;
Broad and expansive, like a valley;
Chaotic, like muddy water.

Who can still muddy water and gradually make it become clear?
Who can make the still gradually become alive through activity?
Those who maintain the Tao do not want to be full.
Just because they are not full they can avoid wearing out and being replaced. "

from
http://www.terebess.hu/english/tao/tamgibbs.html