Have you ever put together a jigsaw puzzle? If so, then you know that a completed puzzle usually makes a picture of something, perhaps a beautiful landscape with mountains and pastures, forests, rivers, and with lots of details like trees and animals and blue sky and clouds above it all. But when you first open the box you discover lots of little pieces of various shapes, each one having only a tiny part of the picture printed on them. Every piece is important, but your goal, of course, is to figure out how the pieces fit together in order to form the whole picture.