The full quote (from Stranger in a Strange Land, Pt. II His Preposterous Heritage, Ch. 1),
“Sit back down—and for God’s sake quit trying to be as nasty as I am;
you don’t have my years of practice. Now let me get something
straight: you are not in my debt. You can’t be. Impossible—because I
never do anything I don’t want to do. Nor does anyone, but in my case I am always aware of it. So please don’t invent a debt that does not exist, or before you know it you will be trying to feel
gratitude—and that is the treacherous first step downward to complete
moral degradation. You grok that? Or don’t you?”
Jill bit her lip,
then grinned. “I’m not sure I know what ‘grok’ means.”
“Nor do I.
But I intend to go on taking lessons from Mike until I do. But I was
speaking dead seriously. ‘Gratitude’ is a euphemism for resentment.
Resentment from most people I do not mind—but from pretty little girls
it is distasteful to me.”
“Why, Jubal, I don’t resent you—that’s
silly.”
“I hope you don’t… but you certainly will if you don’t
root out of your mind this delusion that you are indebted to me. The
Japanese have five different ways to say ‘thank you’—and every one of
them translates literally as resentment, in various degrees. Would
that English had the same built-in honesty on this point! Instead,
English is capable of defining sentiments that the human nervous
system is quite incapable of experiencing. ‘Gratitude,’ for
example.”
“Jubal, you’re a cynical old man. I do feel grateful to
you and I shall go on feeling grateful.”
“And you are a
sentimental young girl. That makes us a perfect complementary pair.
Hmm… let’s run over to Atlantic City for a weekend of illicit
debauchery, just us two.”
“Why, Jubal!”
“You see how deep your
gratitude goes when I attempt to draw on it?”
“Oh. I’m ready. How
soon do we leave?”
“Hummph! We should have left forty years
ago...
As I read it, it's not gratitude per se that he dislikes, it's the sense of indebtedness that generally goes with it. To put it another way, if I do something nice for someone, the last thing I want is for them to feel like they have to pay me back, that they owe me. It's the difference between a gift and a loan. And while the bit about Japanese is probably wrong (I don't speak that language so i can't judge), English doesn't have a good way to differentiate between pure altruism and something given with an expectation of a return. Families and friendships have been torn apart by misunderstandings on this point. In this passage, Jubal is clarifying their social contract to avoid any misunderstanding between them. At this point in the story they don't know each other very well, so it's important to set the ground rules for their relationship.
