About a quarter of the way through The Fighting Soul, Ari Rabin-Havt’s new book about Bernie Sanders’s most recent run for president, a funny little detail emerges. “After he lost his voice in September 2019,” Rabin-Havt writes, “a friend recommended a specific and hard to find brand of cough drop — Grether’s Blackcurrant Pastilles.”(snip) “It was September 2019, rally in Colorado: 10,000 people. And he blew out his voice completely,” he said. A week later, we had the debate. And he sounded terrible. It wasn’t getting better.” Sanders had apparently been eating Halls to no avail when the friend, who’d...