Only the educated are free.
I can, therefore I am.
Never complain and never explain.
Either you run the day or the day runs you.
Well done is better than well said.
Be thine own palace, or the world's thy jail.
Things do not happen. Things are made to happen.
If you can dream it, you can do it.
If you've got a talent, protect it.
The dog that trots about finds a bone.
In hard-core science fiction in which characters are responding to a change in environment, caused by nature or the universe or technology, what readers want to see is how people cope, and so the character are present to cope, or fail to cope.