A windmill can be an important element in a novel for several reasons. It can serve as a symbol of sustainability, renewable energy, or traditional ways of life. It can also be a setting for important events in the story, such as a key meeting or confrontation taking place near the windmill. Additionally, a windmill can provide a sense of place and atmosphere, adding to the overall mood and tone of the novel. Overall, a windmill can be a versatile and meaningful element in a novel, adding depth and complexity to the story.