“When translating prose dialogue one ought to make the characters say things that people talking English could conceivably say. One ought to hear them talking, just as a novelist hears his characters talk.”

Source: Fahrenheit 451

Variant: and it ought to make us feel ashamed when we talk like we know what we're talking about when we talk about love.
Source: What We Talk About When We Talk About Love

Source: The Picture of Dorian Gray

"The Art of Fiction No. 11" (1955)
Context: Well, I haven't consciously tried to develop [a style]. The only thing I've consciously tried to do was put myself in a position to hear the people I wanted to hear talk talk. I used the police lineup for I don't know how many years. [... ] I was just over on the South Side and got rolled. But they gave me a card, you know, to look for the guys in the lineup, and I used that card for something like seven years.

Source: Excerpts of letter to his first wife (14 July 1975)

Source: Culture series, Use of Weapons (1990), Chapter II (p. 417).
Context: He shrugged. “Whatever.”
“Aw, Darac, come on; argue, dammit.”
“I don’t believe in argument,” he said, looking out into the darkness (and saw a towering ship, a capital ship, ringed with its layers and levels of armament and armor, dark against the dusk light, but not dead).
“You don’t?” Erens said, genuinely surprised. “Shit, and I thought I was the cynical one.”
“It’s not cynicism,” he said flatly. “I just think people overvalue argument because they like to hear themselves talk.”
“Oh well, thank you.”
“It’s comforting, I suppose.” He watched the stars wheel, like absurdly slow shells seen at night: rising, peaking, falling...(And reminded himself that the stars too would explode, perhaps, one day.) “Most people are not prepared to have their minds changed,” he said. “And I think they know in their hearts that other people are just the same, and one of the reasons people become angry when they argue is that they realize just that, as they trot out their excuses.”
“Excuses, eh? Well, if this ain’t cynicism, what is?” Erens snorted.
“Yes, excuses,” he said, with what Erens thought might just have been a trace of bitterness. “I strongly suspect the things people believe in are usually just what they instinctively feel is right; the excuses, the justifications, the things you’re supposed to argue about, come later. They’re the least important part of the belief. That’s why you can destroy them, win an argument, prove the other person wrong, and still they believe what they did in the first place.” He looked at Erens. “You’ve attacked the wrong thing.”

Source: Soul Mountain (1989), ch. 81, p. 505

Source: Where I'm Calling From: New and Selected Stories