Before the first World War, humans didn't know about the horrors of industrialized warfare. The Germans had powerful machine guns that could easily decimate the enemies, resulting in trench warfare with no-man's land in the middle of the two enemy lines. This is the horror that all of Europe discovered through WWI, and the novelist's decision to depict it through the eyes of a simple naturist is not an accident—Malouf chose Jim as the protagonist because Jim's character clearly demonstrates the true effect of the war in world politics.
Jim spends his early life observing beauty, and paying attention to all the little nooks and crannies of nature, watching for birds. His life is paradise, because he has become a servant to nature, and he gets to spend each day reveling in his Edenic home.
How different that is than the Western Front! He quickly learns that his ability to pay attention to the details is going to make his experience of an already unimaginably gory and violent war all the more traumatic and horrifying.
But that isn't for nothing. The same way he finds God in little birds, he finds a new type of energy, a darker, horrifying energy, in war. He learns the true nature of human evil, and the true depth of despair and violence that humans are capable of causing. But more importantly, he learns that humans are not especially important on the earth, and though he is certainly forced into an existential crisis, his awareness of beauty and nature provide him with the knowledge that the earth will keep turning, and the birds will still migrate in their seasons, and life will go on. This Solomonic awareness grants him a beautiful death.
