No physicist or chemist today questions the value of a single theory that describes and explains a wide variety of phenomena, but oddly enough, the authors have frequently been asked why they are interested in advancing a unified theory of visual communication. The simplest answer is: to treat visual communication as a science, and seeking unified theories is just what'science does. In more practical terms, a unified approach to visual communication allows us to teach visual design students relatively few things that will enable them to do relatively many things.