More than a quarter-century after completing his term of office, James Earl Carter is still to be found in the thick of debates about national policies on a range of issues: nuclear arms, Iraq, North Korea, and, especially, the conflict between Israel and the Arabs. A steady stream of books and articles continues to issue forth from his pen, and he travels the world on self-selected diplomatic missions. No other former President has chosen to play a similar role. But then, Carter’s whole political career has been out of the ordinary. In order to understand the man today, it is...