Considered by many as a founder or precursor of 20th-century existentialism , his Notes from Underground -LRB- NUMBER@1 -RRB- , written in the embittered voice of the anonymous `` underground man '' , was called by PERSON@1 the `` best overture for existentialism ever written .

He is sometimes considered to be a founder of existentialism , most frequently for Notes from LOCATION@1 , which has been described by PERSON@1 as the best overture for existentialism ever written .
