Why do some authors have more than one theme to their novel? What is the significance of that?

That merely means that there was more than one point they wanted to make.

Sometimes one 'life lesson" is strongly related to others.

What do you mean by one life lesson is strongly related to others?

Each theme is a main point an author wants the readers to understand -- a lesson about life.

Another way to think of themes is to ask yourself, "What is the hidden message?" Or when there are multiple themes, "What are the hidden messages?"

Authors often incorporate multiple themes into their novels to add depth and complexity to their storytelling. Having more than one theme allows authors to explore various aspects of human experience, tackle different ideas and issues, and create a richer, multi-dimensional narrative. Here's how you can understand the significance of multiple themes in a novel:

1. Exploration of Complex Ideas: Having multiple themes allows authors to delve into a range of complex ideas within a single work. Each theme can represent different perspectives, beliefs, or questions about life, society, morality, or any other subject. By addressing multiple themes, authors can offer a nuanced portrayal of their chosen subjects, leading to a more thought-provoking and engaging reading experience.

2. Reflection of Real Life: Real life is seldom simplified to a single theme. People and societies are complex, and various ideas, conflicts, and emotions coexist. By incorporating multiple themes, authors mirror this complexity and realism, creating a more authentic representation of the world we live in. It helps readers to relate to the story and characters on a deeper level.

3. Layered Storytelling: Multiple themes allow authors to craft layered storytelling, where different elements of the narrative intersect and interact. Themes can reinforce, contradict, or juxtapose with each other, creating tension, suspense, and thematic depth. This multifaceted approach enhances the overall complexity and richness of the story, making it more intellectually stimulating and emotionally resonant.

4. Individual Interpretation: Having multiple themes often invites readers to interpret and analyze the text in various ways. Each theme might resonate differently with different readers based on their personal experiences, beliefs, or cultural backgrounds. This open-endedness encourages active reader engagement, as individuals can relate to and find meaning in different aspects of the novel based on their unique perspectives.

To appreciate and understand the significance of multiple themes in a novel, it is important to closely read the text, critically analyze the ideas presented, examine the relationships between different themes and characters, and consider the broader context in which the novel was written. By doing so, you can gain deeper insights into the author's intentions and messages, and potentially uncover your own personal interpretations and connections to the themes explored in the book.