You know how, after you watch a movie with a surprise ending, you sometimes replay the plot in your head to find the clues you missed the first time around? That’s what I’ve been doing lately with the history of conservatism — a movement I had been part of since my teenage days as a conservative columnist at the University of California at Berkeley in the early 1990s. In the decades since, I have written for numerous conservative publications and served as a foreign policy adviser to three Republican presidential candidates. It would be nice to think that Donald Trump is an anomaly who came out of nowhere to take over an otherwise sane and sober movement. But it just isn’t so.

Upon closer examination, it’s obvious that the history of modern conservative is permeated with racism, extremism, conspiracy-mongering, isolationism and know-nothingism. I disagree with progressives who argue that these disfigurations define the totality of conservatism; conservatives have also espoused high-minded principles that I still believe in, and the bigotry on the right appeared to be ameliorating in recent decades. But there has always been a dark underside to conservatism that I chose for most of my life to ignore. It’s amazing how little you can see when your eyes are closed!