These words of Solzhenitsyn, perhaps unwittingly, evoke the core of centuries-old Roman Catholic teaching that man is of two natures -- one good -- one evil. The two are always in conflict and it takes diligence, faith and fortitude to keep on the side of good. (I've read all of Solzhenitsyn's works and, I could be wrong, but I do not believe Catholic teaching influenced him. It's the genius of the man to have come up with the dual nature of man concept.)
Non-believer Sigmund Freud "filched" the Catholic concept when he wrote of the "inner room" of the mind.......which Christians know as "conscience" sorting out the conflicts within us.
And nobody has ever written of man's duelling inner forces better than genius author C.S. Lewis (a Catholic) in his remrkable book, The Screwtape Letters.
I did have to listen liberal BS tho. That is what turned me. The rotting straw of the New York Times, the intellectual prisons of our univerisities, the mindless chants of the left.
Solzhenitsyn was a Russian Orthodox Christian, and like most Christians, was surely aware of the writings of Paul regarding the two natures of man battling it out. This knowledge is available to any Bible reader.
C.S. Lewis was not a Roman Catholic. He was raised an Anglican, but as his spiritual biography Surprised by Joy indicates, he was truly "converted" to Chrisitianity as an adult and it was an outgrowth of conversations with believers of several denominations and of course, the Holy Spirit. He was not particularly affiliated with any Christian church or denomination, but struggled in his faith as an individual (not recommended as we all need fellowship).