What did Donald Trump do today?

He accused "liberal activists" of activism.

Members of Congress, especially Republicans, have been getting an earful about Trump from constituents at public meetings. This appears to have been what prompted Trump to tweet today that "so-called angry crowds in home districts of some Republicans are actually, in numerous cases, planned out by liberal activists. Sad!"

Trump is correct that his political opponents (emboldened by Trump's abnormally low approval rating) are encouraging voters to make their voices heard. This is a cornerstone of American democracy enshrined in the First Amendment, which forbids laws "abridging the freedom of speech... or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances."

There is no truth to the related claim advanced recently by Trump and his surrogates that anti-Trump voices are paid. In fact, paying large groups of people to create the illusion of political support is so rare in American politics (most likely because of the cost) that there is only one confirmed case in recent memory--Trump's campaign kickoff in 2015.

So why is that such a bad thing?

• It's very bad if a president cannot accept that Americans might legitimately have a problem with him.

• Presidents who live in glass White Houses shouldn't throw stones.

• It is actually not a problem if Americans assemble to petition the government for redress of grievances.