Usually, when I write, the seed of my narrative is a specific scene: in my mind I see a specific place, and in this place there are some people, and these people become aware of each other, or of some new or changing aspect, and this new awareness provides an impulse for them to begin to interact or interact differently. This impulse for a social interaction is where I start from, and everything else grows naturally from there: I sit down with this seed of an idea and write it down and just keep writing until the story is finished.
What I do is, I have this "film still" and I discover the story that this moment was taken from.
Now, I have an idea that does not naturally grow into a story. Basically, it is not an idea about how something in a specific person's life changes, so it does not provide an impetus for any specific person's actions. It is not a story idea at all, but a message or theory that I would like to wrap into a narrative, instead of describing it in an essay or a philosophical text book.
I need to keep my ideas to myself, until I have written them, so as not to lose the impetus to write, so I'll give an example of a similar idea:
You believe that eating meat is not good for your health, and now you want to write a story that transports this message in an entertaining way and illustrates the positive effects of not eating meat.
How to do go about finding a plot for an idea like this? Or do you know of any books, websites or other tools, that provide help in such a situation?