Once upon a time, a small cadre of dreamers came to share an aspiration to render the operations of the economy manifest and comprehensible by comparing its configuration to that of rational mechanics. It was a simple and appealing vision of continuous motions in a closed world of commodity space, uniformly propelled toward an equilibrium of forces; the forces were the wants and desires of individual selves. Each and every agent was portrayed as a pinball wizard, deaf, dumb, and blind to everyone else. Not everyone who sought to comprehend and control the economy harbored this particular vision; nor was the portrayal uniformly dispersed throughout the diverse cultures of the world; but the more people were progressively trained in the natural sciences, the more this dream came to seem like second nature. After a while, it no longer qualified as a dream, having graduated to a commonplace manner of speech. Economics was therefore recast in something tangible as the theory of a particularly simple kind of machine.