Theme: that elusive concept that is difficult to craft into one's writing and even more difficult to explain. It's one of those things, in a well-written book, that can make you shake your head in awe at the author's skill in weaving it through her story, leaving you with the firm knowledge that the tale wouldn't be nearly as fulfilling without its presence. And yet, when one sits down to write a book, it's a great challenge to simply state the theme (i.e. this book is going to be about justice or redemption). Actually, I will confess that as I go on in this writing career, it becomes much easier to do just that - so take heart, those of you who are just beginning your writing journey - but it's rarely a piece of cake, any way you slice it.
What, exactly, is theme? To me, it's a concept, symbol, or feeling that is woven into a text, usually from beginning to end, providing a sort of anchor for the characters and actions in a story. Finding your theme is necessary, I believe, if you are to have a full, meaty, and complete tale once you're finished writing. It's what separates the merely entertaining from the ultimately moving, I think, and it will bring your work to a new level, if you are able to isolate and define it.
So how does one go about learning to define theme, in order to incorporate it into one's work?
The easiest way, I think, is to start with the classics. You can then check your perceptions of the themes contained therein against the critical writings that abound, seeing how close to or far from the mark you've come. Take, for example, any of the many works of William Shakespeare; all have been written about extensively. Many are well-known. Choose one - say, Hamlet - and try to isolate the themes in the text. Even if you've never studied the play formally, just a straight reading would likely reveal to you that there is a great deal of deception and attempted deception going on through the course of the drama. Deception, therefore, becomes one of the hallmarks of the play and is likely one of the themes as well.
How about the works of Edgar Allan Poe? Many of his stories revolve around disease, revenge, death, or human cruelty - so likely these could be described as the themes of many of his works.
In my own books, I've seen a tendency for myself as an author to write about the themes of justice, redemption, betrayal and honor. It's just what I keep coming back to and what seems to push my buttons as a writer. It's not too difficult, really, to find your own themes, once you get the hang of it. After you've written a manuscript or two, look at what motivates the characters, what much of the action seems to revolve around - what makes the story tick. Once you see your themes, it's a short step to pumping them up a bit, to make that story sing. Give it a try - I doubt you'll be disappointed with the results!