Chapter 12 returns to the fundamental questions of design and looks at possibilities for computer technology opened up by the understanding developed in the preceding chapters. After briefly reviewing the relevant theoretical ideas outlined earlier, we examine some of the phenomena to which design must address itself, illustrating our approach with a concrete example. We also consider design in relation to systematic domains of human activity, where the objects of concern are formal structures and the rules for manipulating them. The challenge posed here for design is not simply to create tools that accurately reflect existing domains, but to provide for the creation of new domains. Design serves simultaneously to bring forth and to transform the objects, relations, and regularities of the world of our concerns.