According to the philosopher C.S. Peirce the diagram is a system of interrelated parts that operates in a manner similar to another system of interrelated parts. It is a mental map of relations. It drives an open-ended inquiry on a given problem. In architectural discourse a diagram is often defined as a particular form of drawing. It is a simplified image and/or it uses a notation system. In this context, the latter is termed a digital diagram. However, an architectural medium has material properties that influence both the making and the translation of the drawing. It is both a singular artefact and a set of instructions for actions undertaken in another space than that of the medium. This article introduces the notion of an immanent diagram to discuss how the composition of a drawing is distributed. The proposition is that the architectural diagrammatic inquiry operates in the struggle between digital and analogue diagrams. I develop the argument using a traditional architectural drawing as a starting point. In the last section, I discuss a contemporary computer based design practice in which drawings and prototype modelling constitute a heterogeneous technological environment
