The title itself conveys one of the themes of "The Sun Also Rises." Taken from the Book of Ecclesiastes, the passage is believed to have been written by King Solomon, who himself was disillusioned with life and found it meaningless at the end:
The sun also riseth, and the sun goeth down, and hasteth to his place where he arose.
The characters in Hemingway's novel are ones whom Gertrude Stein names "the lost generation": those who died in the war lost their lives, those who lived lost their purpose. After the disillusionment of World War I life has become meaningless; the sun rises and sets and nothing meaningful changes. Thus, Hemingway's novel challenges the American Dream in this disillusionment with progress and regeneration.
A prevalent theme, then, is The Meaning of Life. The characters must reject the heroic life as they have seen that it mainly leads to death. The romantic life, as embraced by Cohn is rejected, too, as Brett says, "He is not one of us." Others feel that the essence of life is mangaing one's money. Unfortunately, several of the characters are not able to do this, either. To keep his mind off his impotence, Jakes tabulates everything in life: "You could get your money's worth." Another thing Jack has paid for is the literature of Turgenieff that he reads; from this literature he gleans from the effort of reading, an effort that he can utilize to recover from the war. In the nihilist philosophy of Hemingway himself, his characters must find their own meaning in life; they must create their own existences and not rely upon any promises that the rising sun may hold.