Documentary filmmaker and left-wing activist Michael Moore had a revelation about the legal age to vote in America after Nikolas Cruz killed 17 people with a legally purchased AR-15 rifle at Marjory Stoneman Douglas High School in Parkland, Florida.

Michael Moore took to Twitter on Monday and shared the “one thing” he says we’ve “learned” since last month’s horrific mass shooting.

“If there’s one thing we’ve learned since Parkland, it’s that the voting age should be lowered to 16. Other countries do it, we should too.”

If there's one thing we've learned since Parkland, it's that the voting age should be lowered to 16. Other countries do it, we should too. — Michael Moore (@MMFlint) March 26, 2018

Moore was among the throng of celebrities who took to social media to shower praise on the thousands of students and activists who hit the streets in Washington, DC, and in other cities across the country and marched in support of gun control.

“I’d say at least one million people in the streets of DC! Historic!” Moore Tweeted on Saturday. “This photo doesn’t even show the full breadth of it. Thank you Parkland students and kids everywhere. You have made it clear to the adults: ‘Either join us or get out of the way. We are here & we are coming.'”

I’d say at least one million people in the streets of DC! Historic! This photo doesn’t even show the full breadth of it. Thank you Parkland students and kids everywhere. You have made it clear to the adults: “Either join us or get out of the way. We are here & we are coming.” pic.twitter.com/pjdBTsyz8J — Michael Moore (@MMFlint) March 24, 2018

The logic of lowering the legal voting age to 16 has been circulated by several celebrities in recent weeks.

“The future belongs to this generation and they fully realize it. Let let them vote. Change voting age to 16,” said actress Mia Farrow.

The future belongs to this generation and they fully realize it. Let let them vote. Change voting age to 16. https://t.co/YyF22O1Mxu — Mia Farrow (@MiaFarrow) March 24, 2018

Simpsons writer Mike Scully wrote, “Raise gun-buying age to 25 and lower voting age to 16.”

Raise gun-buying age to 25 and lower voting age to 16 — Mike Scully (@scullymike) March 24, 2018

Blondie guitarist Chris Stein responded to a tweet from Rep. Steve King (R-IA), saying, “A) I haven’t heard any teenager say that B) voting age should be 16 C) you’re a dipshit.”

A) I haven't heard any teenager say that B) voting age should be 16 C) you're a dipshit — chris stein (@chrissteinplays) March 27, 2018

Countries that allow its citizens to vote at 16 include corruption-ridden Brazil and Cuba, which hasn’t head a free and open election in more than 50 years.

Follow Jerome Hudson on Twitter @jeromeehudson