If you’ve been following Donald Trump’s presidential candidacy and his effect on the Republican primary closely, you were perhaps beset Monday by a strange sense of speechlessness—one born less of ineffability than of tedium.

Trump’s plan to prohibit Muslim immigration into the U.S. is indeed extreme, but to students of the Trump phenomenon and conservative politics more broadly, it was neither unexpected nor the source of any new or profound lesson.

While closing the country to foreign Muslims altogether is a radical idea relative to our founding ideals and current policy, it is but an incremental step relative to the outer bounds of legitimate debate in the GOP primary. Republican presidential candidates have supported discriminating against Muslims in our refugee policy, and opposed the very notion of a Muslim-American president, all without subjecting themselves to universal condemnation. The most surprising part of the latest Trump story is that it proves a Republican candidate can take Islamophobia too far for his party’s tastes.

For most liberals, and for the Trump-backing or Trump-curious segments of the right, the Trump phenomenon needs little further explanation. The only people who claim to be befuddled by the Trump phenomenon are officials on knife-edge in the party he leads.

On the left, the view that Republicans allowed the conservative grassroots to turn their party into a political action committee for white ressentiment has evolved over the years from an argument into a creed. Since at least 2012, liberals have been warning (at times mockingly, but never disingenuously) that by indulging and at times fanning the hostilities and procedural extremism of this part of their coalition, Republicans were letting expediency get the better of them.