Breyten Breytenbach, the award-winning Afrikaans poet, described today how he began to "doubt my sanity" in the total isolation of the "walled pit" of his maximum security cell in Pretoria Central Prison. He was giving evidence for the second day running at the Pretoria Palace of Justice where he is on trial under the Terrorism Act and 17 other charges under the Riotous Assemblies and Prisons Acts. ...He is alleged to have tried to bribe a warden to let him escape. Mr Breytenbach was arrested early in 1975 after he had returned to South Africa after years of self-imposed exile in Paris to organize white activists into bringing about radical change in South Africa.