Famed whistleblower Mark Felt aka Deep Throat died yesterday of heart failure in Santa Rosa, California at the age of 95. In 1972 Felt was instrumental in helping Washington Post reporters Bob Woodward and Carl Bernstein break open the infamous Watergate scandal, which remains one of the most important events in American history.

At the time, Felt was an FBI operative frustrated by the slow pace of investigation into a break-in at Democratic Party Headquarters at Washington, D.C.’s Watergate Hotel. It seemed clear to him that Republican operatives—possibly directed by President Richard Nixon—were likely involved, and that they were sabotaging the FBI investigation. Felt took matters into his own hands by secretly meeting with Bob Woodward during the Post’s investigation of the crime.

At these meetings, which took place in the dead of night in a Virginia parking garage, Felt gave Woodward crucial FBI information. They agreed that Felt’s identity could not be revealed, and that was when Woodward coined the Deep Throat moniker. Felt coined his own immortal phrase: “Follow the money.” That advice helped keep Woodward and Bernstein moving in the right direction during their investigation, and today is a mantra for investigative reporters seeking the truth behind political scandals, as well as an almost universal insight into human motivation.

When the Watergate scandal broke, Nixon resigned the presidency rather than be impeached. The event is often cited as the first major blow to the American public’s belief that their presidents were incorruptible. In that way, Mark Felt helped usher in an age of political cynicism. When he finally revealed his true identity in 2005, the Watergate saga was replayed and he was criticized and praised anew for his role. But whether hero or traitor, he is without question one of the most important Americans of his time.