Writing a book can feel a lot like putting a puzzle together… with the difference that you only have a vague idea as to how the final thing is going to look like (and more often than not it changes in the process). The thing is that you usually have a starting point, otherwise you can’t really get started, but once you are done with the edges you have a huge span of emptiness with few clues as to what goes where. As you near the end, on the other hand, there are only a few sections to fill in, and far fewer pieces to fill them with, the end result: if you’ve done it right, you will reach a point where the story will basically lead you towards its natural end.