If you like that, I would also read Chapter 1 of Bernstein's Four Pillars of Investing. Bernstein's books are all more or less re-writes of the same book multiple times in an attempt to make the Bogle/indexing idea approachable for different audiences. In addition to If You Can, Chapter 1 of Four Pillars is a history of securities returns and is the best thing I've ever read in terms of getting into the right head-space for long-term investing and thinking about risk.

http://www.efficientfrontier.com/t4poi/Ch1.htm

The rest of the book is good, too, but you can just read If You Can instead.