Ahmed Mohamed Kathrada, South African Anti-Apartheid activist, a close colleague of Nelson Mandela, and a fellow Robben Island prisoner died on Tuesday, from complications of a cerebral embolism in Johannesburg at age 87.

Kathrada, who is fondly known by the nickname, ‘Kathy’ was born to Indian immigrants parents on August 21, 1929, in Northwestern South Africa. He was convicted alongside Mandela in the Rivonia trial in 1964 which drew the attention of the world to the brutal legal system during the apartheid regime. Following Kathadra’s death, only two of the eight Rivonia Trialists are still alive – Andrew Mlangeni and Denis Goldberg.

Retired archbishop Desmond Tutu said Kathrada was “a man of remarkable gentleness, modesty and steadfastness,” calling him a moral leader of the anti-apartheid movement.

“These were people of the highest integrity and moral fibre who, through their humility and humanity, inspired our collective self-worth – and the world’s confidence in us,” Tutu said.

Cyril Ramaphosa, South Africa’s deputy president described Kathrada as “a beloved comrade, father, and friend”. He added: “He will be remembered as an unassuming freedom fighter, whose wisdom, tolerance, humility, steadfastness and humour earned him the love and respect of our people.”

Neeshan Balton, head of the Ahmed Kathrada Foundation, said, “‘Kathy’ was an inspiration to millions in different parts of the world. This is great loss to the ANC, the broader liberation movement and South Africa as a whole.”

The ANC, in a statement, said South Africa had “lost a titan”. “His life is a lesson in humility, tolerance, resilience and a steadfast commitment to principle.”

Kathrada’s life as an activist began at the age of 17 when he left school to work full-time for the Transvaal Passive Resistance Council against the Asiatic Land Tenure and Indian Representation Act, which is referred to as the “Ghetto Act”. This act limited the political representation of Indians and defined the areas where they could live, trade and own land. Through the growing co-operation between the African and Indian Congresses in the 1950s, he came in contact with African National Congress leaders such as Nelson Mandela and Walter Sisulu.

In October 1963, he became one of the accused in the famous Rivonia trial and was charged with sabotage and attempts to overthrow the government. Kathrada was sentenced to life imprisonment along with Nelson Mandela, Walter Sisulu, Govan Mbeki, Andrew Mlangeni, Billy Nair, Elias Motsoaledi, Raymond Mhlaba and Denis Goldberg when the trial ended in June 1964.

While in prison, he obtained four university degrees – Bachelor’s degrees in History/Criminology and Bibliography, Honours degrees in History and African Politics from the University of South Africa. While still in prison, Kathrada was also awarded four Honorary Doctorates from the University of Missouri, Michigan State University, and the University of Kentucky. On 15 October 1989, He was released from Johannesburg prison along with Jeff Masemola, Raymond Mhlaba, Billy Nair, Wilton Mkwayi, Andrew Mlangeni, Elias Motsoaledi, Oscar Mpetha, and Walter Sisulu.

Ahmed was imprisoned 26 years and three months and he spent 18 of those years on the Robben Island. When the apartheid ended, he served from 1994 and 1999 as parliamentary counsellor to president

Last year, he was part of a movement of veteran figures who were critical of the governing ANC, especially President Jacob Zuma who has been entangled in several allegations of corruption. Kathrada wrote an open letter to him and called on him to step down.

A popular quote attributed to Kathrada goes thus, “Hatred‚ revenge‚ bitterness – these are negative emotions. The person harbouring those emotions suffers more.”  In a tribute to Mandela in 2013‚ he wrote: “To me‚ over the years he had become the father I had lost in 1944. I could‚ and did turn to him for the most personal advice. Now I have lost you‚ my older brother‚ comrade and leader.”

He is the author of a book, No Bread for Mandela – Memoirs of Ahmed Kathrada, Prisoner No. 468/64 and his foundation – Ahmed Kathrada Foundation – strongly advocates for human rights causes such as youth development, anti-racism, and freedom of speech.