When Sir Isaac Newton published his theory of gravitation in Principia Mathematica in 1687, he prefaced the work with a disclaimer: "Therefore let the reader beware of thinking that by words of this kind I am anywhere defining a species or mode of action of a physical cause or reason." Newton insisted he was making mathematical observations about centers attracting and forces acting on objects, not explaining causal relations.

Scientists don't sit around in their labs trying to establish generalizations. Instead they engage in mystery-solving essentially like that of detective work, and it often involves a creative, imaginative leap.