Heaven and earth last forever.
The reason why heaven and earth last forever
is that they do not live for themselves.
Hence, they last forever.
Therefore, the True Person leaves self behind
and thus is found in front,
is not guarded and thus is preserved,
is self-free and thus is able to find fulfilment.
English text credits : http://www.thebigview.com/tao-te-ching/chapter07.html