ABSTRACT
Visual display of information is older than any language. Graphical display of data, particularly quantities, is more recent. Accurate maps portray distance and land mass sizes. A rope connecting a float, pulley, and counterweight may show current water level. A sundial casts a shadow indicating the hour. The later invention of clocks with dials was inspired by the sundial’s circular shadow motion. Common to these historical points is that information flow is in one direction: the user sees, but cannot control the phenomena giving rise to the data by the display mechanism.
