Anyone who has clicked the popular button that commands a spreadsheet computer program to make a chart has experienced the satisfaction of seeing a confusing grid of numbers resolve into crisp bars. It is hard now to imagine how we ever got by without visual tools for understanding masses of data. But of course such devices as the bar graph, the time-series line graph and the pie chart had to be invented. The peculiar man who came up with all three was William Playfair (1759-1823), a Scot who was convinced he could influence Britain's course with visual explanations of macroeconomic trends. Endowed with drafting experience and confident in the power of graphical language, he presented his polemics in a new form: annotated graphs that vividly highlighted trade gaps and the growing national debt.
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