There are currently at least two opposing ways of understanding the term ‘diagram’. Some see diagrams above all as an aid to systematisation — “problem solvers, because they ‘automatically support a large number of perceptual inferences, which are extremely easy for humans’” —, while others see them as “proliferators of a process of unfolding” or “maps of movement”. If in the former case the visual diagram is regarded in terms of the potential for order and visualisation, for example in mathematics, economics, statistics or pedagogy, in the latter case it is rather the structural possibility of putting relationships in the foreground, so conceiving of the diagrammatic as something which describes the alignment of words, shapes, objects and persons. If the first concept of the diagram is retrospective — by means of diagrams, a complex thought process or argument can be composed or a set of circumstances systematised — the second concept is projective, with vectors pointing in unknown directions. And while in recent years much attention has been paid to the first concept of the diagram in semiotics and image, but also in the science of cognition, the second concept of the diagrammatic has been marked by the power and subject theories of Michel Foucault as well as Gilles Deleuze and Félix Guattari. It is not a question, however, of two fundamentally different types of diagram; rather, this oscillation between systematising and openness is inherent in the diagram. Kenneth Knoespel calls to mind the Greek etymology of the word diagramma, whose roots suggest not only that “which is marked out by lines, a figure, form, or plan, but also carries a secondary connotation of marking or crossing out”. Correspondingly, diagrams would not only take care of “order and stability” but would also be a means to “destabilisation and discovery”.