The somewhat self-evident idea of drawing as an active medium is, in many ways, foreign to its historical application in architecture. Architectural drawing maintains a uniquely precarious position between its instrumentality in the process of building and its perception as a minor art form. The result is an uncomfortable double negative whereby the creative potential of architectural drawing is absent from both of these descriptions as an instrument or an art form. This loss, as a form of absence in architectural drawing’s creative potential, is examined in this essay. It traces the arguments for architectural drawing in the two seminal essays: ‘Translations from drawing to building’ (1986) by the architectural historian Robin Evans, and ‘Lines of work: On diagrams and drawings’ (2000) by the architectural philosopher Andrew Benjamin. Comparing Evans’s and Benjamin’s analyses of Pliny the Elder’s account of the origin of painting, it is revealed that loss is a requirement to free architectural drawing from its seconded position to realisable buildings. Embracing loss enables architectural drawing to be perceived as an incomplete, insoluble medium capable of perpetual change. And, rather than operating as a medium that falsely claims to define the spatial experience of buildings, architectural drawing is argued to instead contribute as an active element to an economy of creative mediums exploring expanded ideas of spatial practice.