In the book The Once and Future King, what was the lesson the Wart learned as a goose?

In The Once and Future King, Wart learns from the geese to not idealize war, underscoring the theme that might is not right. He learns primarily from a goose named Lyo-lyok. When Wart asks her if the geese are at war, Lyo-lyok misunderstands the core of Wart's question: 

“Fighting?” she asked doubtfully. “The men fight sometimes, about their wives and that. Of course there is no bloodshed—only scuffling, to find the better man. Is that what you mean?” (White 169).

When Wart clarifies that he means war and battle, not just "scuffling," Lyo-lyok grows angry and answers sharply: 

“What a horrible mind you must have! You have no right to say such things. And of course there are sentries. There are the jer-falcons and the peregrines, aren’t there: the foxes and the ermines and the humans with their nets? These are natural enemies. But what creature could be so low as to go about in bands, to murder others of its own blood?” (White 170). 

Lyo-lyok remains angry, offended, and confused, especially when Wart asks about if the geese fight each other over boundaries. She highlights that boundaries are just “imaginary lines on the earth” that hold no weight (White 170). She emphasizes that other war-hungry creatures—like humans and ants—would undergo a radical change of heart if they could only zoom out, see the world from the skies, and realize that there are no such things as boundaries (and, in turn, recognize that these artificially imposed territories are no reason to fight one another).
Lyo-lyok’s reaction to war sharply contrasts with that of Wart—who, even after being lectured on the atrocities of killing one’s own kind, still says, “I like fighting. . . . It is knightly” (White 170). Lyo-lyok answers plainly, “[You like war] Because you’re a baby,” pointing out that Wart's idealization of war stems from his immaturity (White 170).