On the fourth episode of "From the Catbird Seat," Rob Casper chats with former Poet Laureate Natasha Trethewey, who reflects on her 2013 conversation with singer-songwriter Rosanne Cash at the Library of Congress. We'll listen to clips from that event, which navigates the power of lyric language, the intersections of songwriting and poetry, and the influence of the two artists' fathers—Johnny Cash and Eric Trethewey.