 In the final years of the 20th century and the early years of the 21st , more such choral symphonies were written . Krzysztof Penderecki 's Seventh Symphony was for the third millennium of the city of Jerusalem . Tan Dun 's Symphony 1997 : Heaven Earth Mankind commemorated the transfer of sovereignty over Hong Kong that year to the People 's Republic of China . Philip Glass 's Fifth Symphony as one of several pieces commissioned to celebrate the beginning of the 21st century . Paul Spicer 's choral symphony Unfinished Remembering ( 2014 , libretto by Euan Tait ) was commissioned to commemorate the centenary of the outbreak of the First World War . 
