It is in the early Middle Ages that the demonstrative effectiveness of drawing begins to be correlated to mathematical description, thus laying the foundations for the geometrical conceptualization that technical drawing makes measurable. The biunivocal procedures that make it possible to transcribe three-dimensional shapes and to trace from these their exact collocation in space, their real size and their real shape, arose from the experience of specialized building site craftsmen and from the study of classical works. The new figure emerged that of the master mason who could draw and interpret designs. The need to show or to see what the end product would look like before it was actually built brought about the refinement of a drawing system from which the professional figure of the architect emerged.