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Meryl Streep‘s passionate Golden Globes speech came straight from the heart.

A source tells PEOPLE that the legendary actress, who delivered the now-viral speech while accepting the Cecil B. DeMille Award Sunday evening, wrote the words herself. It was something Streep felt very passionate about, the source added.

Streep was unavailable for further comment.

The Florence Foster Jenkins star focused her acceptance speech on President-elect Donald Trump, although she never mentioned him by name. She also spoke at length about an incident on the campaign trail when he appeared to mock a disabled reporter during a rally.

“It kind of broke my heart, and I saw it, and I still can’t get it out of my head because it wasn’t in a movie,” Streep said of the incident. “It was real life. And this instinct to humiliate when it’s modeled by someone in the public platform by someone powerful, it filters down into everybody’s life because it kind of gives permission for other people to do the same thing.”

She continued, “Disrespect invites disrespect. Violence incites violence. The powerful — use definition to bully others, we all lose.”

The president-elect spoke briefly with The New York Times over the telephone following the award show, telling the paper he was “not surprised” that he was attacked by “liberal movie people” and referred to Streep as “a Hillary lover.”

Early Monday morning, he continued to blast Streep in a series of tweets, calling her one of the “most over-rated actresses in Hollywood” and insisting that he wasn’t mocking a disabled reporter but was instead trying to imitate his alleged “groveling.”

Since then, celebrities have come out in force to support the actress, who has received threats from Trump supporters in response to her speech, multiple sources confirm. George Takei, Billy Eichner, Elizabeth Banks and more stars were quick to come to Streep’s defense on social media,

On Monday, George Clooney commented on the incident to PEOPLE, asking Trump sarcastically, “Aren’t you supposed to be running the country?”