Legally speaking, people own copyright on their own posts. You could probably include a small excerpt under 'fair use' provisions (in the USA, anyway), though.
The simplest and most ethical way to go is probably just to ask the poster for permission to quote them.
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When people see things as beautiful, ugliness is created.
When people see things as good, evil is created.
When the way is forgotten, 'morality' and 'piety' need to be taught.
-Dao De Jing, Chapter 2 |