For four years in the mid 1990’s Matt Damon and Ben Affleck were unknown actors with minor credits (School Ties, Dazed and Confused) trying to attract interest in their screenplay Good Will Hunting.

The pair wrote the screenplay in the hope that it would launch their acting careers. In trying to sell it, they attached a condition — the two of them star in the film as best friends Will and Chucky.

Damon and Affleck struggled to attract interest from studios unwilling to invest in untried talent. When they did eventually find a studio willing to cast them, there were more complications in getting the right director and the right draft of the script.

Around that time, Damon had just been cast as the lead in Francis Ford Coppola’s The Rainmaker and it was through Coppola that the boys were able to get the script to Robin Williams, who was at the peak of his career.

Williams read it and loved it. He agreed to take on the role of Sean Maguire, the psychologist whose relationship with Will Hunting is at the heart of the film.

Robin Williams in New York in 2002. Photo: Getty

In 2009, all of Good Will Hunting’s key players gave Boston Magazine an oral history of the film. Williams said.

“I read it and went, ‘This is really extraordinary’. The Sean character had such history that I was going, ‘Where did it come from?’ I found out later that it’s based on Matt’s mother and Ben’s father, kind of a synthesis of the two,” he told Boston Magazine.

Once Williams came on board the film was finally on the fast track.

“Robin really was the ‘rainmaker’,” Affleck said. Williams became the linchpin to the studio finally green lighting the film.

In order to create a feeling of authenticity for the film’s Boston setting, Williams went on a tour of local, south Boston bars with Damon and Affleck, which was nearly disastrous. The locals did not take kindly to them.

On set, Williams’ famed knack for improvisation came to the fore, with Damon remembering:

“The last line of the film. There was nothing scripted there. He opens the mailbox and reads the note that I had written him … When he said, ‘Son of a bitch stole my line,’ I grabbed Gus. It was like a bolt. It was just one of those holy-shit moments where, like, that’s it!”

Good Will Hunting was a huge hit when it was released in 1998, earning over $US225 million at the box office. It was nominated for Nine Academy Awards, winning best Original Screenplay Oscars for Damon and Affleck, and a Best Supporting Actor for Williams — his first win after five nominations.

The film would go on to launch the careers of Damon and Affleck, each separately cementing their place as Hollywood royalty.

In recent days, with the sudden, tragic passing of Williams, both Affleck and Damon have released statements acknowledging the debt of gratitude they owe to Robin Williams in transforming their lives:

With Affleck posting on twitter:

Robin had a ton of love & did so much for so many. He made Matt & my dreams come true. What do you owe a guy who does that? Everything.

— Ben Affleck (@BenAffleck) August 12, 2014

And Damon releasing a statement:

“Robin brought so much joy into my life and I will carry that joy with me forever. He was such a beautiful man. I was lucky to know him and I will never, ever forget him.