W. Mark Felt passed away yesterday at the age of 95. The former number 2 at the FBI was known, for most of his life, for not being known, except to Bob Woodward, to whom he funneled confidential information about the Watergate break-in and the Nixon White House's use of the Justice Department to investigate and undermine political "enemies". Dubbed "Deep Throat" (after a popular adult film of the era), Felt's willingness to speak to the press contributed, ultimately, to President Nixon's resignation.

Last week, we learned of another Deep Throat in our midst; Thomas Tamm, a Justice Department attorney, revealed himself as the source for Eric Lichtblau and James Risen's story on illegal surveillance by the Bush administration. We depend on insiders breaking ranks and breaking the law to protect the public's right to know. What must it be like to be in their position?