A visual display of data should be simple enough to fit on the side of a van
Which is a very Tufte thing to say. When they asked Tufte to speak at the Skeptics Society at CIT, his fee was to see Feynman's van. This was "a 1975 Dodge Maxivan adorned with squiggly lines on the side panels. Most people who saw it gazed in puzzlement, but once in a while someone would ask the driver why he had Feynman diagrams all over his van, only to be told, "Because I'm Richard Feynman!""