This is an idea of stunning fecundity. As you know, an idea book is any collection of anecdotes or stories from which one can derive ideas for expanded articles or essays. This book collects a large number of facts grouped topically and focusing well enough on history to go into my sweet spot.
I read it over the course of a number of months, a couple anecdotes/facts or a chapter at a time. I’m thinking about putting it onto my desk, though, so any time I’m out of ideas, I can grab it, flip to a random page, and then draw something out to draw out into an essay.