This collection of essays forms the second Festschrift to honour the dean of Gustav Mahler research, Henry-Louis de La Grange, on the occasion of his ninetieth birthday. It includes vibrant, new historical, theoretical, and aesthetic research on the complex mind which produced among the best-loved orchestral works and songs of Western classical music. Henry-Louis de La Grange's passion and tireless devotion to Gustav Mahler began when he first heard his Ninth Symphony conducted by Bruno Walter at Carnegie Hall in New York. He went on to plumb the depths of this composer's mind and soul and to explore every facet of his existence. Among the many honours he has gleaned since the publication of the first Festschrift, Neue Mahleriana (Lang, 1997), Henry-Louis de La Grange has been named Professor by the Government of Austria (1998) and Officier de l'Ordre de la Légion d'honneur (2006). He has also been awarded Bard College's Charles Flint Kellogg Award in Arts and Letters, the Österreichisches Ehrenkreuz für Wissenschaft und Kunst, 1. Klasse (2010), the Gold Medal of the Internationale Gustav Mahler Gesellschaft (2010), and an honourary doctorate from The Juilliard School (2010). As another everlasting tribute, the American film director Jason Starr released his documentary film, For the Love of Mahler: The Inspired Life of Henry-Louis de La Grange, in 2015.