"'...our society or culture or what you want to name it, has a life and a right of its own.
"'...if communities didn't resist encroachments, they'd soon be swallowed by the biggest and greediest. Wouldn't they? In the end, dead sameness. No challenges, no inspirations from somebody else's way. What service is it to life if we let that happen?
"'And, you know, enmities needn't be eternal.'" (Rise Of The Terran Empire, p. 661)
(i) We can organize the production and distribution of wealth in such a way that everyone has access to far more than they need and thus that "greed" ceases to motivate anyone. (But that is not the situation at the time of the border dispute between Terra and Ythri.)
(ii) In how many works does Poul Anderson rightly dramatize the point that sameness is bad and therefore diversity is good?
(iii) He mentions Lepanto but there are many other historical examples of former enemies becoming allies and friends. See here.