It has been suggested that the final chapter of The Sun Also Rises is unnecessary, as the conflicts of its major characters were for the most part resolved by the end of Book II. But most novels feature some sort of denouement (literally, "unraveling"), a dramatization, by the author, of the ways in which the world has been changed by the action of the book. (Think of F. Scott Fitzgerald's The Great Gatsby, the final pages of which show us the protagonist's once-perfect lawn now overgrown, with Nick Carraway preparing to return to the Midwest.) One sense in which The Sun Also Rises is a Modern, even radical, book is in its insistence that change (or change for the better, at least) is a myth. After 250 pages overflowing with almost-uninterrupted violence, alcohol abuse, and sex, the novel's characters end up exactly where they began: Cohn is presumed to be with Frances; Bill is in Paris; Mike is still engaged to Brett, who still plans to marry him; and Brett is, of course, miserable, and turning to Jake for comfort — comfort he is all too willing to provide, at the expense of his own sanity.
The early Moderns presumed that technology would make life easier, happier, better. Similarly, the Great War was called "the war to end all wars" — as if human beings had finally evolved to the point where wars would be unnecessary. And yet it is precisely technology, in the form of airplanes and submarines, machine guns and mustard gas, that made the conflict of 1914–1918 so universally devastating. Unlike the American pilgrims on the French train, and even the English tourists from Biarritz, the veterans of World War I who populate The Sun Also Rises know the brutal truth that nothing has changed — that nothing can change, because human nature can't change. Thus, the only possible ending for this book is one that mirrors the beginning, with the awesomely attractive and yet profoundly destructive Brett once again taking advantage of Jake's decency and desire. In fact, Brett has actively refused to change — for Romero, who requested that she grow her hair out (that is, behave more conventionally for the sake of his pleasure). On the other hand, she does resist his charms and insist that Romero leave her for his own good, and this, indeed, seems evidence of growth.
