Book excerpt: By adapting Freud's notion of "floating attention" to urban systems, Mario Gandelsonas applies a process of visual drift to the plan of Chicago. He uses mechanical eye of the computer in a "de­layering" process to read the plan of the city and to discover the system of urban notions that are specific to the American grid. Gandelsonas explores the spatial relationships between physical and abstract realities in the Chicago River area, the One-Mile Grid and its subdivisions. By high­lighting the anomalies and idiosyncrasies of the grid the moments where its regularity falters, he establishes a narrative of Chicago's urban text. In separate essays Catherine Ingraham, Joan Copjec, and John Whiteman explore the philosophical, psychoanalytic, and urbanistic dimension of this provocative analysis.