The problem of two-dimensional spatial localization, as Lotze and Helmholtz understand it, is the problem of assigning a unique, eye-relative (or “oculocentric”) direction to every point in the visual field. Lotze’s commitment to mind-body dualism precluded looking to any physical or anatomical spatial ordering in the visual system for a solution to this problem (Lotze 1887 [1879]: §§276–77). Rather, Lotze maintains that every discrete visual impression is attended by a “special extra sensation” whose phenomenal character varies as a function of its origin on the retina. Collectively, these extra sensations or “local signs” constitute a “system of graduated, qualitative tokens” (1887 [1879]: §283) that bridge the gap between the spatial structure of the nonconscious retinal image and the spatial structure represented in conscious visual awareness.