A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Invent the question
Engaging sources
Part I. Research and writing: from planning to production

Now comes a tricky part. It's like reverse engineering: you've found the answer to a question that you haven't yet asked, so you have to reason backward to invent the question that your new generalization answers. In this case, it might be What signs indicate the significance of masks in the societies of those who make and use them? As paradoxical as it may seem, experienced researchers often discover their question after they answer it, the problem they should have posed after they solve it.