In July 1972, I was on a train tour through Florida promoting the film The Candidate. Entertainment and political press were on board, and I heard them gossiping about a break-in at Democratic National Committee headquarters at the Watergate complex in Washington. The story was being covered by two young reporters, Mr Bob Woodward and Mr Carl Bernstein from The Washington Post.
The reporters were at the infancy of an investigation that would come to be known as Watergate, the greatest political scandal in modern American history. But at the time it was simply a few small articles about a break-in.
As time went on, I became fascinated with their story. It occurred to me it might make a good film - two hard-working journalists struggling to get to the truth. My first idea was simply to make a movie about two reporters, the importance of journalism and freedom of the press. It was only later that the depth of the Watergate scandal was discovered.
I tried to get in touch with Mr Woodward and Mr Bernstein.
It didn't go well. At first, they refused my calls, fearing they were being duped by the Nixon administration into some type of set-up. We finally made contact and eventually made a movie about their story, All The President's Men. This year marks the 45th anniversary of the Watergate scandal. Because of my role in the film, some have asked me about the similarities between our situations in 1972 and 2017.
There are many. The biggest one is the importance of a free and independent media in defending our democracy.
When President Donald Trump speaks of being in a "running war" with the media, calls them "among the most dishonest human beings on earth" and tweets that they're the "enemy of the American people", his language takes the Nixon administration's false accusations of "shoddy" and "shabby" journalism to new and dangerous heights.
Sound and accurate journalism defends our democracy. It's one of the most effective weapons we have to restrain the power-hungry. I always said that All The President's Men was a violent movie. No shots were fired, but words were used as weapons.
In fact, I had a hard time getting producers interested in All The President's Men. "Newspapers, typing, journalism - there's no drama here" - so the critique went. I didn't see it that way. To me it was a story about two journalists hell-bent on getting to the truth. That's the movie, but the real-life Watergate scandal didn't have just two people searching for the truth. It had an entire cast of characters in minor and major roles who followed their consciences: President Richard Nixon's counsel John Dean, whose testimony blew open the congressional hearings; Attorney-General Elliot Richardson and Deputy Attorney-General William Ruckelshaus, who both resigned rather than followed Nixon's demand to fire special prosecutor Archibald Cox; and, most of all, congressional Democrats and Republicans.
Nixon resigned from office because the Senate Watergate Committee - its Democratic and Republican members - did its job. It's easy now to think of Watergate as a single event. It wasn't; it was a story that unfolded over 26 months and demanded many acts of bravery and honesty by Americans across the political spectrum.
The system worked. The checks and balances the Constitution was designed to create functioned when put to their biggest test. Would they still? Which brings me to the other half of the question: What's different now?
Much. Our country is divided, and we have a tenuous grasp on truth.
There was a time during a period of national crisis when politicians from both sides of the aisle put partisan politics aside to uncover the truth. There was a time when Democrats and Republicans united to navigate a peaceful ending to a corrupt and criminal presidency. There was a time when members of Congress placed defending our democracy above party interests for the greater good. There was a time.
Now is a different time. If we have another Watergate, will we navigate it as well? In a statement in May 1973, Mr John Dean addressed what he described as efforts to discredit his testimony by discrediting him personally. He famously said: "The truth always emerges." I'm concerned about its chances these days.
•The writer is an actor, director, producer and environmental activist.