Text in English and German. This monograph describes the construction of reality through the cognitive subject, and, associated with this, potential ways for producing space. The book studies methods for exposing, through indeterminacy, the definition of space to a larger field of possibility within personal interpretation, and thus virtually de-bordering space. Against a historical background of past attempts to de-border space visually, new possible ways of indeterminately defining space through the modulation of light are shown. The analysis of various modulation phenomena is illustrated with references to works of art, and the phenomena are studied with a view to integrating them in the actual production of space. The modulation of light has the potential of creating diffuse and ambivalent characteristics on space-defining surfaces. This fuzziness offers an opportunity for a freer interpretation of spatial definition and thus also for de-bordering space due to the process of perception. New materials and technologies can be used to create spatial worlds that open up genuine, hitherto unknown realms of cognition and experience. Based on multilayered, ambiguous spatial situations, according to the author, new open spaces of perception are possible and thus an expansion of human consciousness as well with respect to the world around us.