This essay is an attempt to enrich the discourse on an epistemological research through design based on Henri Lefebvre's meta-philosophy (Paris 1965). The meta-philosophy refers back to the human daily routine and the poetic exploration of practice as a premise for philosophical tradition. I use Lefebvre's thoughts in their relation of theory and empirical knowledge, to build a bridge to Design Sciences as a practice-oriented research. To underline the basic approach of a Design Science based on practice, the analysis is developed along a specific design project that operates with a "research through design" Frayling (1993/94). This allows to show, how concept- and theory development interlink with the designing practice of the researcher himself. The essay tries to develop a Design Science, which includes the subjective perspective of the designer himself as well as the phenomenological character of design processes.