"Bad books on writing and thoughtless English professors solemnly tell beginners to 'Write What You Know', which explains why so many mediocre novels are about English professors contemplating adultery."
And then the opening lines from his best known book, The Forever War:
"Tonight we're going to show you eight silent ways to kill a man." The guy who said that was a sergeant who didn't look five years older than me. So if he'd ever killed a man in combat, silently or otherwise, he'd done it as an infant.
I already knew eighty ways to kill people, but most of them were pretty noisy. I sat up straight in my chair and assumed a look of polite attention and fell asleep with my eyes open.