Themes are the fundamental and often universal ideas explored in a literary work.
World War I undercut traditional notions of morality, faith, and justice. No longer able to rely on the traditional beliefs that gave life meaning, the men and women who experienced the war became psychologically and morally lost, and they wandered aimlessly in a world that appeared meaningless. Jake, Brett, and their acquaintances give dramatic life to this situation. Because they no longer believe in anything, their lives are empty. They fill their time with inconsequential and escapist activities, such as drinking, dancing, and debauchery.
It is important to note that Hemingway never explicitly states that Jake and his friends’ lives are aimless, or that this aimlessness is a result of the war. Instead, he implies these ideas through his portrayal of the characters’ emotional and mental lives. These stand in stark contrast to the characters’ surface actions. Jake and his friends’ constant carousing does not make them happy. Very often, their merrymaking is joyless and driven by alcohol. At best, it allows them not to think about their inner lives or about the war. Although they spend nearly all of their time partying in one way or another, they remain sorrowful or unfulfilled. Hence, their drinking and dancing is just a futile distraction, a purposeless activity characteristic of a wandering, aimless life.
World War I forced a radical reevaluation of what it meant to be masculine. The prewar ideal of the brave, stoic soldier had little relevance in the context of brutal trench warfare that characterized the war. Soldiers were forced to sit huddled together as the enemy bombarded them. Survival depended far more upon luck than upon bravery. Traditional notions of what it meant to be a man were thus undermined by the realities of the war. Jake embodies these cultural changes. The war renders his manhood (that is, his penis) useless because of injury. He carries the burden of feeling that he is “less of a man” than he was before. He cannot escape a nagging sense of inadequacy, which is only compounded by Brett’s refusal to enter into a relationship with him.
While Jake’s condition is the most explicit example of weakened masculinity in the novel, it is certainly not the only one. All of the veterans feel insecure in their manhood. Again, Hemingway does not state this fact directly, but rather shows it in the way Jake and his veteran friends react to Cohn. They target Cohn in particular for abuse when they see him engaging in “unmanly” behavior such as following Brett around. They cope with their fears of being weak and unmasculine by criticizing the weakness they see in him. Hemingway further presents this theme in his portrayal of Brett. In many ways, she is more “manly” than the men in the book. She refers to herself as a “chap,” she has a short, masculine haircut and a masculine name, and she is strong and independent. Thus, she embodies traditionally masculine characteristics, while Jake, Mike, and Bill are to varying degrees uncertain of their masculinity.
Sex is a powerful and destructive force in The Sun Also Rises. Sexual jealousy, for example, leads Cohn to violate his code of ethics and attack Jake, Mike, and Romero. Furthermore, the desire for sex prevents Brett from entering into a relationship with Jake, although she loves him. Hence, sex undermines both Cohn’s honor and Jake and Brett’s love. Brett is closely associated with the negative consequences of sex. She is a liberated woman, having sex with multiple men and feeling no compulsion to commit to any of them. Her carefree sexuality makes Jake and Mike miserable and drives Cohn to acts of violence. In Brett, Hemingway may be expressing his own anxieties about strong, sexually independent women.