Answer: Gustav Mahler 

Gustav Mahler (1860-1911) was an Austrian composer and conductor. He created his Symphony No. 8 in E Flat major, also called the "Symphony of Thousand," in 1906.

Often hailed as one of his greatest works, Symphony No. 8 was first performed in Munich, Germany, on September 12, 1910. It was a massive and demanding work that required multiple choruses, a number of soloists, and a 100+ piece orchestra. Prior to coming to the United States, Philadelphia Orchestra conductor Leopold Stokowski had heard the symphony performed in Germany. Once he had established himself with the orchestra, he sought to bring the "Symphony of a Thousand" to America. His persistence paid off when he conducted the piece in Philadelphia to droves of eager listeners in early March 1916.

In a note to audiences about the symphony, Stokowski wrote: "For six years I have wished to produce the work of Mahler, but not until now have I had the adequate resources. I do not know how sufficiently to thank all who have co-operated, and especially the directors of the Orchestra for their generosity and large vision."

A few items on Mahler's 8th Symphony and it's first American performance in Philadelphia are available in the HSP collection of Academy of Music programs, playbills, and scrapbooks (#3150). Additional photos of the Philadelphia Orchestra, its musicians and conductors, can also be found in the Philadelphia Record photograph morgue (V07).