I feel like the anecdote about Stonewall Jackson really helped prove a big point about how wonderfully useful maps can be. He used a map, essentially information interpreted by another person, to see something that could not be seen otherwise. Maps really provide an opportunity to see something that might not be ordinarily seen. In this case it was strategic information during the Civil War. The ultimate usefulness of Stonewall's map was not seen until the right situation arrived, where the information the map provided what precisely what he was looking for. In many other situations the same map may have proved itself utterly useless, but at this point in time the information available was exactly what was called for. Perhaps it is fair to say that the more often a map can provide the right information at the right time the more useful it is.