A book project is big — it'll take a ton of great content and a series of solid connections to get from A to Z. You get there by absorbing and synthesizing material until you have enough puzzle pieces to complete the picture.
Sometimes, taking a problem on head-on isn't the most creative solution. Why not try Oblique Strategies, the I Ching, or a coin flip? Changing your mental approach can lead to a side-door solution you didn't see before.