In 1945 Aleksandr Solzhenitsyn was sentenced to eight years' imprisonment for making a slighting remark about Stalin in a letter. Recalling this experience in the novel The First Circle, he wrote that “the methodical indifference of the procedure was such as utterly to break the prisoner's will”.

Solzhenitsyn's genius was in depicting the remorseless oppressiveness of Soviet rule. Abitrary brutality - especially if driven by ideological fervour - can in time lose impetus. Solzhenitsyn dramatised a phenomenon more terrifying: a system of total oppression, in which political dissent is treated literally as a form of madness.

There remains among Western commentators a surprisingly persistent mythology of Soviet rule. This depicts Stalin as the usurper of Lenin's revolutionary asceticism, with Khrushchev and his successors tempering the bloodiest excesses. In reality, the grey bureaucracy of Khrushchev and Brezhnev laid claim to the individual mind. It defined political difference as mental illness.

On being released from the camps, Solzhenitsyn became the voice and dramatist of the zeks, the prisoners who languished in a system where the merest idiosyncrasy was an antisocial act. He became, with the dissidents Andrei Sakharov and Anatoli Scharansky, a towering moral witness against this system. And he was fearless.

Times Archive, 1976: Warning to the West

We offer you the experience of our suffering; we would like you to accept it without having to pay the monstrous price of death and slavery

• Leading article: The warning and the hope

• Solzhenitsyn expelled from Russia

• Nobel award to disgraced writer

His most famous work, One Day in the Life of Ivan Denisovich, was published in 1962, when political sclerosis in the Kremlin enabled a modest loosening of censorship. This short novel, about a former inmate of the camps, dramatised what even Khrushchev could regard as an aberrant part of the Soviet system. Solzhenitsyn, however, was not a critic merely of revolutionary excesses. As he later demonstrated with his novel Lenin in Zurich, he was concerned to expose the entire cult of the founding father of the Russian Revolution. The book could be circulated in Russia only in clandestine editions.

Solzhenitsyn was, however, a case apart from the other famous dissidents. His was more than a political message. He was part of the Russian tradition of the novelist as prophetic witness. The parallels with Fyodor Dostoevsky are close. In imprisonment and exile, both testified to the power of the human spirit to withstand adversity. But his message was not always one calculated to inspire admiration in the West.

In common with Dostoevsky, Solzhenitsyn's indictment of autocracy sat oddly - to Western readers at least - with his wider philosophy. He was hostile to the notion that Russia should adopt liberal constitutionalism. He was committed to the values of the Russian Orthodox Church against the corrupting influences of Western materialism. He was fervent in his belief in the unity of Russia and the Slavic peoples. In a notorious interview last year, Solzhenitsyn defended the regime and foreign policy of Vladimir Putin. Some critics have even accused Solzhenitsyn of anti-Semitism - one parallel with Dostoevsky that is certainly unfair.

These characteristics were integral to Solzhenitsyn's faith and philosophy. He was an extremist. Yet without that burning sense of mission, the characteristics more congenial to Western liberal humanists might never have prospered. Solzhenitsyn was one of the great men, as well as one of the great artists, of the last century.