Gertrude Stein's notebooks reveal her acute awareness of a constitutive feature of late nineteeth- and early twentieth-century urban life, the grid. The grid structure, as a model of visual and material organization, characterizes and is consolidated across legible environments from the visual-textual integration of the printed page to the design of city streets, becoming the definitive paradigm of modern spatio-temporal experience. Stein's notebooks for "Subject-cases: The Background of a Detective Story" demonstrate that Stein, in playing with the grid, not only subjects its basic features to rearrangement through her diagrammatic method but also uncovers its political foundations.