These two have had a centering effect on me at certain times in my life:
"Invest in yourself. Material things come to those who have self-actualized."
-- from a post on Craigslist."When I breathe my last breath, I will not die, it is the world that will end.
-- unknown philosopher that influenced Ayn Rand. Makes you think, huh?
A couple from my favourite physicist:
"For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled."
-- Richard P. Feynman, likely after the Challenger disaster, which Feynman helped investigate.
"I'll never make that mistake again ... of course, you only live one life, and you make all your mistakes, and learn what not to do, and that's the end of you."
-- Richard P. Feynman
One of my own:
"Culture doesn't define us, we define our culture."
And one more just for fun:
"That's it for me! Goodnight everybody!"
-- George Castanza