Stephen Sondheim died last week at his home in Roxbury, Conn. He was 91. For six decades, Mr. Sondheim, a composer-lyricist whose works include “Sweeney Todd” and “Into the Woods,” transformed musical theater into an art form as rich, complex and contradictory as life itself. “For me, the loss that we see pouring out of Twitter right now and everywhere you look as people write about their memories of Sondheim is for that person who says yes, devoting yourself to writing or to dancing or to singing or to composing — or whatever it is — is a worthwhile life,” Jesse Green, The Times’s chief theater critic, said in today’s episode. “And there really is no one who says that as strongly in his life and in his work as Sondheim does.” Today, we chart Mr. Sondheim’s career, influence and legacy.