Verse 81: The Sage and human civilisation.

信言不美 美言不信。
Honest words are not sweet, sweet words are not honest. (It also implies that sweet words are insufficient to build a strong relationship. They open the path, but more is needed to successfully follow through).
善者不辯 辯者不善。
Charitable people do not argue, people who argue are not charitable.
知者不博 博者不知。
Those who are enlightened do not store (names, fact), those who store are not enlightened.
聖人不積。
The sage accumulates nothing. (However, those who accumulate nothing may not be sages.)
既以為人己愈有。
Since he does everything for man, he gets everything.
既以與人己愈多。
Since he gives everything to man, he gets plenty.
天之道利而不害。
The movement (tao) of heaven benefits without hurting.
聖人之道為而不爭。
The behavior (tao) of the sage actualises his goals without causing discord.

This final verse talks about applying the Tao to civilised life and living with other human beings. The two characteristics of civilisation are speech and accumulution. The sage can't care less.The emphasis here is humanistic, showing how a sagely attitude towards others naturally reflects the path of heaven. Heaven here is an umbrella term for nature and must be thought apart from the "heaven and earth" framework. Finally, all the talk about "wu wei" (non-being), ultimately leads to enlightened being, that achieves without sowing discord.