When Trump launched his n+1st vileness on Twitter yesterday, retweeting phony and incendiary videos (talk about “fake news”!) posted by a lunatic-fringe white Christian Muslim-hating British website,

Britain First

, the reaction from anti-racists was quickly and rightly outraged. Britain First traffics in demographic panic that can be summarized easily: The white Christians are vanishing! THEY are taking over.

Its chiefs, in particular deputy leader Jayda Fransen, roam Europe, not just Britain, crusading against Muslims and mosques. After being arrested at a Belfast rally, she popped back in a video to call her arrest evidence that “Britain has become Sharia compliant and our establishment has now instituted legislation that constitutes blasphemy laws here in the U.K.” This was way too much for Prime Minister Theresa May, whose spokesman declared after Trump’s retweets:

Britain First seeks to divide communities by their use of hateful narratives that peddle lies, … stoke tensions, … cause anxiety to law-abiding people. … [T]he prejudiced rhetoric of the far right … is the antithesis of the values this country represents, decency, tolerance and respect.

Nevertheless, May declined to lift her invitation for a Trump state visit.

Britain First is a fringe sect whose videos are slapped-up, scattershot, mislabeled, and concocted shouts of fire in crowded theaters. Ordinarily, though, they have limited reach. Even after a massive boost from Trump, their Twitter subscribers number 27.3 thousand. Trump’s blast away to 43.6 million. This is how the fringe migrates mainstream. This is how a trickle-down of vileness acquires a fire hose.

But the big story doesn't stop with Trump's globe-wide gift to the worst devils of human nature. It's not even that Sarah Huckabee Sanders defended the tweets on the ground that, whether or not the videos are true to reality, “the threat” [of Islam] is real.” The big story is that Trump, or his trusted Ministers of Internet Intake, inhabits a bottom-barrel world in which Fox News and Infowars and Gateway Pundit and—sure—Britain First loom large. They’re picking this stuff up, combining through it, repurposing it all the time.

They're picking it up selectively and combing it to weaponize it most efficiently. As The Guardian pointed out, “The Islamophobic videos were originally tweeted by Fransen on Tuesday afternoon and Wednesday morning before being picked up by Trump. They were not sequentially posted, meaning the president would have had to scroll through her timeline before picking out which videos to retweet.”

Martin Callanan, the Conservative Party’s Minister of State at the Department for Exiting the European Union, told the BBC: “I can only assume [Trump] has made a mistake and that he didn’t realize who Britain First were.” But no, Trump doesn’t make that sort of mistake. Along with the rest of what he is pleased to call his “movement,” he lives in an intellectual universe, if we can call it that, where race-hatred, Islamophobia, Jew-hatred, and refugee-hatred are the overpowering themes.

To anyone paying attention, this has been crystal-clear since at least early July 2016, when Trump retweeted a red Star of David shape slapped onto a bed of $100 bills—an image derived from the online white-supremacist movement. For at least the fifth time, Trump's Twitter account was sharing a meme from the racist “alt-right” and offering no explanation why. (I wrote about his immersion in online loathsomeness then for billmoyers.com.)

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Ben Kharakh and Dan Primack, at Fortune.com had more detail:

Throughout his campaign, Trump has been blithely recycling tweets from neo-Nazis and white supremacists who revel in the phrase “white Genocide.” They use those tweets, copy them and reuse them. Thus, consciously or not, they flash signals to the Make America White Again crowd—come on board. As one prominent neo-Nazi put it, Trump is “giving us the old wink-wink.”

Kharakh and Primack scrupulously tried to give Trump an out, writing:

It is possible that Trump―who, according to the campaign, does almost all of his own tweeting—is unfamiliar with the term “white genocide” and doesn't do even basic vetting of those whose tweets he amplifies to his 7 million followers. But the reality is that there are dozens of tweets mentioning @realDonaldTrump each minute, and he has an uncanny ability to surface ones that come from accounts that proudly proclaim their white supremacist leanings.

Trump said then that he doesn't pay attention to the source of his tweet material. He sees what he likes and retweets it. Asked by Kharakh and Primack for more detail about his Twitter practice, his spokesperson Hope Hicks “declined to explain how Trump searches through his Twitter feed. Hicks also declined (repeatedly) to answer Fortune's question as to whether or not Trump believes that white genocide is a legitimate concern.”

Here's the point: Trump's Twitter pattern tells you a lot about the crowd he or his Twitter-reading staff hang out with. If you believe that Trump or his top lieutenants just happen to stumble on these racist tweets—singling them out from among the vast universe of possible source materials, perhaps because neo-Nazi design ideas are so “interesting”—then I'll buy you a life membership at Mar-A-Lago and a lifetime supply of Pepto-Bismol to accompany it.

The great big story is not just that Trump lies and bullshits. It's not only that Trump and his campaigners court Americans who want to make America white and Christian again. The problem is not only the vicious and lunatic legions who creep out from under the rocks at his signals. He lives in their world. He breathes their air. Tweets like those of Britain First don't fly onto his screen at will. A slime-pit of race and religion hatred is the universe where Trump and his movement live.