It is not down in any map; true places never are.
—Herman Melville, Moby Dick
Science is about mapmaking. It’s about taking a complicated world and reducing it to some sparse set of markings on a map that provides new guidance across an otherwise incomprehensible, and potentially hostile, landscape. A good map eliminates as much spurious information as possible, so that what remains is just enough to guide our way. Moreover, when the map is well made we gain a deeper understanding of the world around us. We begin to recognize that rivers flow in certain directions, towns are not randomly placed, economic and political systems are tied to geography, and so on.
Maps—and science—are often more about what we leave out ...