I'm curious about how you would go about starting with a theme and building a story off of that. Can anyone give me a hypothetical example of what this would be like? I think I would like to give it a try.
There are different ways to go about it. Take Melville's Billy Budd as an example. It is interpreted by some as thematically addressing tension between positive law and natural law (positive law being man-made law; the law is what it is and is valid because it was set down according to a legitimate process. Natural law, on the other hand, being a law or nature or (more commonly) set forth from the divine, so that it is unalterable regardless of what humans say).
If you decided at the outset that you wanted to explore the theme of natural law v. positive law, you might start thinking up a situation where the outcome would differ depending on which type of law was applied. That gives you tension right there. In Billy Budd's case, under a natural law theory, the idea is that he might well be morally innocent of any crime (a killing, in this case), whereas under the positive law in effect at the time, he is guilty and the punishment is death.
So you go from theme to simply fleshing out a fact scenario that illustrates conflict relating to your theme. Not saying that Melville did this, but you could do it that way and arrive at a story like Billy Budd.