to life imprisonment. Robben Island: 1964–1982 In 1964, Mandela and his co-accused were transferred from Pretoria to the prison on Robben Island, remaining there for the next 18 years. Isolated from non-political prisoners in Section B, Mandela was imprisoned in a damp concrete cell measuring by , with a straw mat on which to sleep. Verbally and physically harassed by several white prison wardens, the Rivonia Trial prisoners spent their days breaking rocks into gravel, until being reassigned in January 1965 to work in a lime quarry. Mandela was initially forbidden to wear sunglasses, and the glare from the lime permanently damaged his eyesight. At night, he worked on his LLB degree, which he was obtaining from the University of London through a correspondence course with Wolsey Hall, Oxford, but newspapers were forbidden, and he was locked in solitary confinement on several occasions for the possession of smuggled news clippings. He was initially classified as the lowest grade of prisoner, Class D, meaning that he was permitted one visit and one letter every six months, although all mail was heavily censored. The political prisoners took part in work and hunger strikes—the latter considered largely ineffective by Mandela—to improve prison conditions, viewing this as a microcosm of the anti-apartheid struggle. ANC prisoners elected him to their four-man "High Organ" along with Sisulu, Govan Mbeki and Raymond Mhlaba, and he involved himself in a group, named Ulundi, that represented all political prisoners (including Eddie Daniels) on the island, through which he forged links with PAC and Yu Chi Chan Club members. Initiating the "University of Robben Island", whereby prisoners lectured on their own areas of expertise, he debated socio-political topics with his comrades. Though attending Christian Sunday services, Mandela studied Islam. He also studied Afrikaans, hoping to build a mutual respect with the warders and convert them to his cause. Various official visitors met with Mandela, most significantly the liberal parliamentary representative Helen Suzman of the Progressive Party, who championed Mandela's cause outside of prison. In September 1970, he met British Labour Party politician Denis Healey. South African Minister of Justice Jimmy Kruger visited in December 1974, but he and Mandela did not get along with each other. His mother visited in 1968, dying shortly after, and his firstborn son Thembi died in a car accident the following year; Mandela was forbidden from attending either funeral. His wife was rarely able to