Robert Kosara of eagereyes (and Tableau) just published a great walk-through of the history of data visualizations. Or, rather, the main goals of different data visualization giants during the course of history. It really gives you a great understanding of why we are now torn between infographics and data visualizations (read: Robert Kosara’s [INFOGRAPHIC] vs. data visualization dichotomy, ie. visuals-first vs. data-first dichotomy; not the static vs. interactive dichotomy).
So, if you want to be better at pinpointing the when and whats of William Playfair, Florence Nightingale, John Snow, Charles Minard, Otto Neurath, Jacques Bertin, John Tukey, Nigel Holmes, and Edward Tufte do read The Changing Goals of Data Visualization.