The window is an opening, an aperture for light and ventilation. It opens it closes; it separates the spaces of here and there, inside and outside, in front of and behind. The window opens onto a three-dimensional world beyond: it is a membrane of where surface meets depth, where transparency meets its barriers. The window is also a frame, a proscenium: its edges hold a view in place. The window reduces the outside to a two-dimensional surface; the window becomes a screen. Like the window, the screen is at once a surface and a frame—a reflective plane onto which an image is cast and a frame that limits its view. The screen is a component piece of architecture, rendering a wall permeable to ventilation in new ways: a “virtual window” that changes the materiality of built space, adding new apertures that dramatically alter our conception of space and (even more radically) of time.