Edward Tufte from the library and just kept on renewing. There was something new to marvel at on every page, whether it was Durer's woodcuts of string instruments from 1532 or Johann Bayer's sky maps from 1603 or the illustrated, hideous packing grid of a slave ship.
Tufte has an impressive CV. A professor at Yale, he has made it his life work to examine how visual evidence brings clarity to critical analysis. This particular book is full of images that have impressed him as aids to critical thinking. You can't help but learn things as you turn each page, like David Hockney's mapping of the angles in old world masters' paintings to show how they may have used mirrors to help them reproduce elements.
Tufte also pokes tremendous fun at Powerpoint presentations and argues convincingly that it may actually be responsible for the dumbing down of corporate America.
President Obama recently appointed him to the Recovery Independent Advisory Council. I wonder if anyone was silly enough to do a Powerpoint presentation when they first convened?