The Origin of Ideas [Open Blog Post]

One thing that I've always been confused about is where ideas come from. I understand that writers can be inspired by the world around them (events, people, images, etc.), but I don't get how they can turn that inspiration into concrete stories and plotlines. Take, for example, the Harry Potter series (I love these books - I also talk about them in my Literacy Narrative). J.K. Rowling may have been inspired by the battle between good and evil, but where did the rest of the story come from? Where did the notion of Quidditch come from?

I guess people just come up with ideas like that. I wish my brain could do that with as much ease as every published author seems to have. Whenever I try to write, I find myself struggling for ways to make my works sound original, not just repetitions of what I've read before. To help with this, maybe I could try brainstorming for at least 10 minutes before I write. (According to Everything's An Argument, brainstorming is an extremely effective way to generate concepts .) Also, maybe I can make an outline before I start writing, instead of just going like I usually do. I think that having more time to work with the material might give me more inspiration. Finally, I can keep a journal or something about little parts of life that give me ideas. That way I'll be able to look back on previous experiences and remember exactly what it was that sparked my ideas.

All in all, I still have my question: where do ideas come from? If anyone out there on the internet besides my teacher is reading this and has answers, just let me know!