Consider La Fontaine's fable "The Lion and the Mouse":
One day, a Lion was taking a nap when a mouse started running over him. The Lion woke up, put his paw on him, opened his mouth and prepared to swallow him.
- Forgive me! - cried the mouse - Forgive me this time and I will never forget it. Who knows if one day you won't need me?
The Lion was so amused by this idea that he lifted his paw and let him go.
Days later, the Lion was caught in trap. As the hunters wanted to offer him alive to the King, they tied him to a tree and set out to find a way to transport him.
Seeing the sad situation the Lion was in, the little Mouse gnawed the ropes that held him.
And that's how a tiny mouse saved the King of the Animals.
Moral of the story: We shouldn't underestimate others.
The theme of a story is the subliminal message present, expressed or explored by the narrative. According to the texts of Aesop or La Fontaine, the Moral of the story.
This message, most often, addresses some aspect of the human condition. Love, Loneliness or Happiness are the most used but even those can be much more detailed and specific, depending on the narrative itself.
If we quickly analyze several famous books and movies, we notice that there are all kinds of topics that we can cover.
The Lord of the Rings talks (among other themes) about the Industrial Revolution and how it made the magic of the unknown world disappear. The Terminator speaks of the various problems of rapidly evolving technology. Saving Private Ryan is about perseverance and sacrifice, even to those we do not know.
All stories have a subliminal message to pass on to the reader, even if the author did not plan it in the first place, it is exactly this message, this moral, this theme, that makes the stories stay in our memory.
Opposite to the plot and the arc of the characters, the theme develops at a gut level. It comes entangled in the meanwhiles left by the different components of the narrative and, at the same time, covers it like a unifying mantle.
You don't read it, you feel it. It is expressed in the actions of the characters, in the description of the wind or even in the tone of the narrative.
When we finish reading a book and are left with that feeling of grief, happiness or any other, it is the Theme of that book that resonates within the depths of our being. The Aspect of Human Nature discussed in there made us relate to that narrative and made us feel something connected with our own individual experiences.
How to insert the Theme in your narrative?
Well, for that you'll have to use all the other gears that are part of your story. You can use the Dialogue between characters, important moments of your plot or even the various elements of Worldbuilding. What matters is that you don't do it openly.
Never take your readers for stupid or dumb by explaining everything. Theme must be imperceptible. Invisible, almost. However, when your reader finishes reading your work, it's the theme that will pop up and give you a punch in the stomach.
When choosing the Theme, don't worry if you're talking about what thousands of writers before you have already talked about. Love has been used so many times but it remains one of the main used themes as there are several perspectives and lenses through which we can analyze this Theme. Like people, Love can happen in millions of ways and with millions of different outcomes.
If you have an original way to tell a love story, do it. Think of the movie P.S. I love you and how it changed the so-called Chick Flicks.
Finally, if you don't have a predefined Theme for your story, don't worry. It will emerge from it during the writing process because every narrative has Theme, even if it is not noticeable on the surface.
We all have a moral that we want to convey when we tell a story. They don't come out without a purpose.
The worst that can happen is having to lose a little more in editing, in order to combine the loose pieces. In fact, that's what happened to me and it was only after a few (quite a lot!) chapters written that I started to explore the Theme, which made me want to go back and reconfigure the narrative to accommodate some aspects of the new message.
