Michael Ignatieff in conversation with Irina Ratushinskiaya

At the Chelsfield Room, Southbank Centre.

Michael Ignatieff, the BBC's resident, late-night intellectual is worried about the sightlines he tells us, peering around the hall with his hand cupped over his eyes. If he looks this way - he skews his body in the rather uncomfortable looking chair - he can address so many people, but not all of the people, whereas if he sits this way ...

Irina Ratushinskiaya, the Odessan poet and novelist who was sentenced to seven years hard labour in a camp during the 1970's for anti-Soviet propaganda (ie. the writing of poems) smiles indulgently across at him. Her look seems to say should this man be tangling with these minor contingencies on such a serious occasion as this one?

Ratushinskiaya and Ignatieff are here to have a conversation about life in the Soviet Union during the 1970's. The great threat of that decade was the psychiatric hospital - which, it was widely feared, could change a man or a woman's personality forever. But what is it exactly about poetry that the KGB feared? Ignatieff asks. Why did the authorities confer such importance upon the words of a young girl such as Ratushinskiaya, who was 16 at the turn of that decade?

"I would like to say it is because poets are the natural spiritual leaders of mankind, something like that, but that would not be true," she replied. Her accent is very thick and glottal, but the voice rings sure and forceful as a hammer on an anvil.

The truth lay in the elusiveness of poetry, the fact that the poet himself - and other people too - could memorise it; the fact that it could not be destroyed in the way that a sculpture could be destroyed, or controlled in the way that a film-maker could be controlled. "They could search anything but the human brain," she said.

The conversation turns to the question of religious faith. Ratushinskiaya was a Christian in the 1970s, and she remains one still. A pendant containing an image of a religious icon hangs at her neck. Had her faith wavered in prison? A woman with a quavering voice asks her during questions.

Not at all, Ratushinskiaya replies. Prisoners are on the contrary, privileged people. "You are freshly arrested. Everything has been confiscated. You are isolated, robbed. But your first feeling is not one of despair. It's a sense of security. Now there is nothing more that any human being can do to you. It is a moment of total and utter freedom. You can leave everything behind. Who cares if they kill me? I said to myself then. Tomorrow I shall be in Heaven? She paused. "Now it is not so easy ..."

Ignatieff is mesmerised "I could continue this conversation all night," he says. "Why don't we do that?" Ratushinskiaya replies.