One spring morning last year, I happened to be strolling through the Congressional cemetery east of Capitol Hill with the White House press secretary Dana Perino as she walked her dog. Ms. Perino was candidly describing the challenges of her job, which were only mounting as George W. Bush’s approval rating continued to drop. Then she looked directly at me and said, “But it’s all worth it, because I so believe in the president.” It would have been easy for me to dismiss Ms. Perino as a bright and likable but ultimately Kool-Aid-stricken peddler of talking points, were it not...