EARLY one morning in September 2015 this columnist found himself in a hotel lobby in Greensboro, North Carolina, waiting to board the campaign bus of Ben Carson. The retired brain surgeon was at that point soaring in polls of Republican presidential candidates, coming within a percentage point of Donald Trump, the front-runner. It has been a long, painful slide from that peak to Mr Carson’s announcement on March 2nd that he saw "no political path forward” for his presidential campaign, a day after winning a derisory three delegates in the dozen contests of Super Tuesday.
