Over the years, I've come across several blogs and articles comparing writing to working on a jigsaw puzzle. In some ways the comparison seems apt. As
Patricia Wrede commented in her blog, "Some people start by doing all the edges," which to me is like setting up an outline and filling in the story from the outside in. "Some people do all the trees and houses first", such as the worldbuilding. And then there are those who work on whatever pieces fit together and expand outward, whether it be character interactions, action scenes or quiet moments.
Pat Grant pointed out one problem with the metaphor that I've run into many times - that the jigsaw puzzle usually comes with a cover picture so that the assembler has some idea what the goal is. The writer, however, doesn't always know what the end result will be. Short story? Novella? Novel? Though the author does know whether she is writing a western or a fantasy, the minor details and how they all fit together can often be a surprise.
There is the real life fact that the jigsaw puzzle, whether box or web form, comes with a limited amount of puzzle pieces. An author, however, may often find additional pieces on the mental tabletop. This could be because there are several puzzles jumbled together - either several books of a series or perhaps a couple of completely unrelated books are warring for attention. The latter happens all too often to me, as I'm usually working on more than one story at a time. The problem comes in when I find myself trying to fit one of the YA sf pieces into the fantasy story. It might seem to fit at first, but not with any of the surrounding ones. As long as I can keep my jigsaws separate, though, a good mental break if one puzzle is being stubborn is to switch to a different one.
Occasionally, though a particular piece/idea/character just refuses to fit. That's one advantage the writer has over the jigsaw assembler. If the story works without that piece, it can be pulled out and left to grow its own story/puzzle.
