You don't say what novel you are reading, but I can explain to you how to determine the theme for yourself. A theme is a main idea that the author is trying to get across with his or her work. One way to determine a theme is to try to find words or phrases or events that are repeated at different points in the novel. If the author repeats something, it is likely because he or she wants you to notice them because they are clues to the theme.
Another thing to notice is paradox. If there is a contradiction in a character, or the plot. Paradoxes are used to cause you to ask questions. If you ask why questions about paradoxes, your answers will most likely bring you to the theme.
Well a theme is a recurring or a repeating idea or subject that continues coming throught the whole novel or whatever you are reading (since you don't say the novel you are reading).
hope this helps!