" Well. I don’t see passion as . . . as petrol. Something that runs out. I see it as more like, I don’t know, something you lose. Like keys.” He picks up the pen he’s using to do the crossword and waves it around. “Or this biro.” “Keys get found. Biros don’t. So it’s important for me to know which it is.” Tom doesn’t say anything. “Keys? Or a biro?” Tom doesn’t say anything. Louise is getting angry. "

― Nick Hornby , State of the Union: A Marriage in Ten Parts