This July will mark nearly 70 years since the aborted assassination attempt against Adolf Hitler, which was memorably re-imagined in the 2008 thriller, Valkyrie, starring Tom Cruise as Colonel Claus von Stauffenberg, a righteous military man ashamed of the stain that the Nazis would forever leave on Germany.

The tale behind (or should it be tail?) Payback: The Case for Revenge is very nicely encapsulated on its 99th page, the middle of a chapter entitled The Science of Mad. It is there that otherwise skeptical readers, those who have always been told to "turn the other cheek" and that an "eye for an eye" leads to blindness, come face-to-face with their worst nightmare: Human beings are hardwired for vengeance. It's who we are, embedded in our genes, imprinted in our DNA. Indeed, our evolutionary history has very much depended on the certainty of deserved payback for both our moral and physical survival. Despite what religions have preached and what states have legislated, we can't live without our revenge, nor should we have to.

Order has been restored to Boston after the terrorist bombings near the finish line of its Marathon, but the feelings of anger and rage directed at the two alleged terrorists, and whatever accomplices can be tied to this crime, is very much unfinished business.