Adam Gopnik, former Paris correspondent for “The New Yorker,” provides some context for understanding the “Charlie Hebdo” attack. Also, director Mike Leigh, long known for his trenchant films about contemporary life, turns to one of the titans of 19^th-century art, J.M.W. Turner. And the young composer Matthew Aucoin takes us inside his writing process. Aucoin has drawn comparisons with Leonard Bernstein and Mozart — but he’d rather be himself.