Drawing process : what's a diagram?

Within the architectural universe there have been numerous attempts in recent years to define the term diagram. Etymologically, it means exclusively “through graphic representation”, which does not clarify much (from the Greek, dia, through + gramma, graphic representation). Jennifer Sigler defines it as the minimum graphic element that explains a concept. Federico Soriano borrows from Federico García Lorca, and claims that diagrams are the marrow of form or content. Efforts to clarify the nature of these powerful graphical representations have multiplied at a similar rate as its ever-increasing use in contemporary architectural projects.