, ▁later ▁exist ential ists ▁discussed ▁conflicts ▁of ▁personal ▁principles , ▁cultural ▁norm s , ▁and ▁exist ential ▁desp air . ▁ ▁Music ▁ ▁Ex ist ential ▁ang st ▁makes ▁its ▁appearance ▁in ▁classical ▁musical ▁composition ▁in ▁the ▁early ▁tw enti eth ▁century ▁as ▁a ▁result ▁of ▁both ▁philosoph ical ▁develop ments ▁and ▁as ▁a ▁reflection ▁of ▁the ▁war - t orn ▁times . ▁Notable ▁compos ers ▁whose ▁works ▁are ▁often ▁linked ▁with ▁the ▁concept ▁include ▁Gustav ▁Mah ler , ▁Richard ▁Stra uss ▁( oper as ▁Ele kt ra ▁and ▁Sal ome ), ▁Claude - A ch ille ▁Deb uss y ▁( opera ▁P elle as ▁et ▁Mel is ande , ▁bal let ▁Jeux , ▁other ▁works ), ▁Jean ▁Sib el ius ▁( es pecially ▁the ▁Four th ▁Sym phony ), ▁Arnold ▁Sch o enberg ▁( A ▁Sur viv or ▁from ▁Wars aw , ▁other ▁works ), ▁Alban ▁Berg , ▁Francis ▁P ou len c ▁( opera ▁Dialog ues ▁of ▁the ▁Car mel ites ), ▁D mit ri ▁Sh ost akov ich ▁( opera ▁Lady ▁Mac b eth ▁of ▁the ▁M ts ensk ▁District , ▁sym phon ies ▁and ▁chamber ▁music ), ▁Bé la ▁Bart ók ▁( opera ▁Blue be ard ' s ▁Castle , ▁other ▁works ), ▁and ▁Kr z ysz to f ▁P end ere cki ▁( es pecially ▁Th ren ody ▁to ▁the ▁Vict ims ▁of ▁H iro sh ima ). ▁▁ ▁Ang st ▁began ▁to ▁be ▁discussed ▁in ▁reference ▁to ▁popular ▁music ▁in ▁the ▁mid - ▁to ▁late ▁