In what he described as potentially “the most important words [he has] ever spoken,” acclaimed astrophysicist Neil deGrasse Tyson argued in a video posted to his Facebook that scientific literacy was necessary to uphold the United States and that the current denial of scientific consensus endangered the world.

“When you have people who don’t know much about science, standing in denial of it, and rising to power, that is a recipe for the complete dismantling of our informed democracy,” Tyson said in the video that was intercut with footage from scientific experiments, political speeches, and watershed moments in the U.S. history as well as photographs of leading scientists.

Immediately after this warning, the short film flips through a series of examples of science denial — a clip of Vice President Mike Pence speaking before Congress, as a then-member, played in which he demanded “that educators around America teach evolution not as fact, but as theory,” the rise of anti-vaxxers, climate change denial, etc.

The Trump administration and its proposed budget have been labeled "anti-science." Trump has questioned the veracity of the claim that humans are causing the Earth’s atmosphere to change more rapidly than it otherwise would, in spite of the fact that the overwhelming majority of climate scientists agree on this point. And heads of important science-related agencies like the Department of Energy and Environmental Protection Agency, have previously said those departments shouldn't exist, or in the case of EPA Scott Pruitt, previously sued the EPA over regulatory policies.

Tyson, who lived through the Vietnam War, the Cold War, and the Civil Rights Movement, expressed his frustration that for the first time in his lifetime he lived in an era in which people were in denial about scientific fact.

“When you have an established scientific emergent truth, it is true whether or not you believe in it and the sooner you understand that the faster we can get on with the political conversations about how to solve the problems that face us,” Tyson said.

This isn’t the first time he has stood up for science. In February, Tyson gave a speech at the Greensboro Coliseum in which he said that scientific illiteracy was a threat to the nation.