A quarter of a century behind the curve, but right on time for me: The Hitchhiker’s Guide to the Galaxy. (Also online at h2g2.com)
“Ah,” said Arther. “This is obviously some strange usage of the word safe that I wasn’t previously aware of” (1979, republished 2005, Del Rey, p. 49).
Zaphod says quietly:
“I only know as much about myself as my mind can make out under its current conditions.” (p. 144)
“Perhaps I’m old and tired,” [Slartibartfast continues], “but I always think that the chances of finding out what really is going on are so absurdly remote that the only thing to do is to say hang the sense of it and just keep yourself occupied . . . . What does it matter? . . . I’d far rather be happy than right.”
“And are you?” [asks Dentarthurdent].
“No, that’s where it all falls down, of course” (p. 193).