A motif in literature is a recurring symbol, image or idea that is significant to the overall theme of the work. Some examples of motifs in literature are green lights in "The Great Gatsby," miscommunication in "Romeo and Juliet" and divine intervention in "The Iliad" and "The Odyssey."
A motif is important in developing the theme of a literary work. For example, in Dostoevsky's "Crime and Punishment," psychological turmoil and mental instability are major themes. Dostoevsky uses the motif of crossing bridges to develop this theme, as the main character Raskolnikov experiences a sudden shift in his mental state each time he crosses a bridge while wandering around St. Petersburg.