There was a time when a book could shake the world and on Aug. 17, 1976, a book titled “Roots: The Saga of an American Family” by Alex Haley arrived on bookstore shelves and immediately began to fly off those shelves and into apartments and homes across the country, starting a cultural rumble and sparking national conversations about race and slavery.Excitement had been building quietly for weeks. Then came the reviews, carried in daily newspapers and fueling the fanfare. Writing in the New York Times, James Baldwin began his review with, “I cannot guess what Alex Haley’s countrymen will make...