Our greatest problems involve thinking and the visualization of complexity. By "Thinkertoy" I mean, first of all, a system to help people think. ('Toy' means it should be easy and fun to use.) This is the same general ides for which Engelbart, for instance, uses the term "augmentation of intellect." But a Thinkertoy is something quite specific: I define it as a computer display system that helps you envision complex alternatives. The process of envisioning complex alternatives is by no means the only important form of human thought; but it is essential to making decisions, designing, planning, writing, weighing alternate theories, considering alternate forms of legislation, doing scholarly research, and so on. it is also complicated enough that, in solving it, we may solve simpler problems as well. Ted Nelson, Computer Lib/Dream Machines, Thinkertoys