Commentary The death of composer Stephen Sondheim at 91 is more than the end of an era. It is the end of a chain of great Broadway musicals dating back to the 1920s when Jerome Kern’s “Showboat” first dazzled theater audiences. I met him only once. It was at Barbara Cook’s apartment in New York where she had invited a few friends following her performance of Sondheim songs at Carnegie Hall. When I entered, he was sitting on a couch and talking to someone. When the man left, I sat down next to him. “Mr. Sondheim,” I said nervously, “I can’t think of anything to add to all of the wonderful things that have been said about your work, so I will just say thank you.” He smiled and said, “thank you” and uttered a pleasantry I have since forgotten, because I was in awe of him. In 2008, Sondheim …