The Devil in the White City, Erik Larson's engrossing nonfiction book about the 1893 Chicago World's Fair, and the murders that took place in conjunction with it. This morning I came across this line:
Visitors also encountered the latest and arguably most important organizational invention of the century, the vertical file, created by Melvil Dewey, inventor of the Dewey Decimal System.
When I read that I actually GASPED ALOUD, and immediately turned the corner of the page down, so I wouldn't forget where to find it. I am such a nerd.