The peepshow is a rectangular box; the interior is painted on three sides, as well as on the top and bottom
The sixth side is open; originally light would have entered the box from this side, perhaps through specially treated paper stretched across it. The box would have been placed close to a window or illumination provided by a candle. There are peep-holes in the two shorter sides which provide the illusion of three-dimensional views of the interior of a house.
Hoogstraten’s box is an unusually elaborate example, decorated on the exterior with allegorical paintings which correspond to chapters in a theoretical book that the artist was to write later. The long side illustrates