This series explores the life and music of Gustav Mahler. In "Origins, " Michael Tilson Thomas journeys to the provincial Austro-Hungarian city of Mahler's childhood, traces his musical roots, follows his rise as a young conductor, and, with the help of the San Francisco Symphony, escorts us through the creation and shocking premiere of Mahler's First Symphony. "Legacy" examines Mahler's grand achievements and great sorrows -- his career-crowning appointments in Vienna and New York, and the sudden, tragic death of his daughter -- and shows how his stormy inner life inspired new heights of creativity.