Why is Gustav Mahler’s Symphony No. 8 known as the Symphony of a Thousand?

Gustav Mahler’s Symphony No. 8 in E-Flat Major is known as the "Symphony of a Thousand" because of the massive number of performers required to execute the work, which far exceeded the requirements of any other symphony at the time of its composition.1

The nickname stems from the sheer scale of the musical forces involved; for example, the 1910 premiere featured 1,028 performers. The score calls for a large orchestra (including an abundance of brass, woodwinds, and percussion), an organ, adult and children’s choirs, and eight vocal soloists. Mahler intended the work to be a magnificent, celebratory statement, and he utilized these vast resources to create a soundscape he described as the "whole universe" bursting into song.1