“I don’t like to analyze myself because I might not like what I see.” — Donald Trump, in an interview for Never Enough: Donald Trump and the Pursuit of Success, by business journalist Michael D’Antonio. “Trump was willing to say and do almost anything to satisfy his craving for attention. But he also possessed a sixth sense that kept him from going too far.” — D’Antonio’s conclusion to the book. One often-underappreciated virtue of U.S. presidential campaigns is that their extreme length makes it very difficult to conceal what makes a candidate tick. (Barack Obama in 2008 was an exception,...