 Proper cognition may be pure, as when synthesizing a manifold of pure intuition (e.g., the pure intuition of space or time) with a concept (e.g., the concept of space as discussed in the Metaphysical Exposition of Space in the Transcendental Aesthetic). Proper cognition may also be empirical, as when synthesizing an empirical intuition (e.g., of touch or vision) with a concept. Kant often describes empirical cognition as “experience” (Erfahrung; see, e.g., B166, A176/B218, A189/B234), though empirical intuition and concepts are also related in what Kant calls “perception” (Wahrnehmung).