Many scholars see Dostoyevsky as one of the greatest psychologists in literature. His works have had a big effect on twentieth-century fiction. Very often, he wrote about characters who live in poor conditions. Those characters are sometimes in extreme states of mind. They might show both a strange grasp of human psychology as well as good analyses of the political, social and spiritual states of Russia of Dostoevsky's time. Many of his best-known works are prophetic. He is sometimes considered to be a founder of existentialism, most frequently for "Notes from Underground", which has been described as "the best overture for existentialism ever written". He is also famous for writing "The Brothers Karamazov", which many critics, such as Sigmund Freud, have said was one of the best novels ever written.