“The writer is not only the conscience of the world, but also its nightmare.”
Related quotes

“Your only responsibility as a writer is to be true to the story that has chosen you as its writer.”

“The world may be full of fourth-rate writers but it's also full of fourth-rate readers.”
Occasionally attributed to Walters; actually coined by Stan Barstow.
Misattributed

“A good writer possesses not only his own spirit but also the spirit of his friends.”

Letter to three students (October 1967) as translated in Solzhenitsyn: A Documentary Record (1970) edited by Leopold Labedz (1970) “The Struggle Intensifies".

Source: The 20th century capitalist revolution. 1954, p. 113-114; as cited in Prashker (1954)