Paul Hendrickson

On a rainy September night in 1972, a man on a ferry bound for Martha's Vineyard tried to throw another passenger overboard. The target of the assailant's attack -- former defense secretary Robert McNamara, then president of the World Bank.

The assault received considerable attention at the time though was largely forgotten in the decades that followed. After McNamara's death earlier this month at age 93, the incident was recounted by University of Pennsylvania professor Paul Hendrickson when he was a guest on Rachel Maddow's MSNBC show on July 7.

As she was about to introduce Hendrickson, an incredulous Maddow described the attack and told her audience, "This is not a metaphor" -- which turned out to be exactly how Hendrickson would describe it to Maddow. To which I respond -- it wasn't the only metaphor at work.