If we are to think about diagrams closely, we must register their cognitive significance as they direct work and establish networks of relationships among multiple symbolic fields. Diagrams do not engage a simple horizon of understanding but are part of an integrative process through which structures literally appear in the world. Rather than being hermeneutic in a strict sense, diagrams are heuristic because they are accompanied by an expectation that they participate in a process that turns words and experience into (...) structure. Because diagrams may shift in status, they may be thought of as relays that both create meaning and enable symbolic translation from one mode of representation to another. While a diagram may visually present or reinforce an idea one moment, the next it may provide a means for seeing something never seen before. After commenting on how recent architectural theory has approached diagram, I consider the relationship between diagram and metaphor before turning my attention to the ways that diagrams function within a process that includes design as well as building. Finally, I ask how the use of diagram within architecture points not only to a phenomenology of invention and practice but also to the networks which constitute architecture. (shrink)