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One of Nelson Mandela's closest confidants is still challenging the powers that be, with plenty of guidance from his ancestors, the ancient Greeks.

"Power, even in advanced democracies, is abused. It's part of life," said George Bizos, a Greek-born lawyer who defended Mandela at the 1960s trial in which the anti-apartheid leader was sentenced to life in prison.

After the end of white minority rule, many activists in South Africa branched into other fields or eventually retired. But 85-year-old Bizos, now an executor of Mandela's will, resists retiring from human rights work.

The advocate, who doesn't carry a mobile telephone and wears a big suit jacket that hangs loose on his shoulders, works for the Legal Resources Centre, a South African human rights group. He has hammered at police witnesses during an inquiry into the shooting deaths of several dozen protesters by police during a mine strike at Lonmin's Marikana platinum mine in 2012.

The legal warhorse has tousled white hair, a soft, sometimes quavering voice, describes himself as "computer-illiterate" and sprinkles remarks with references to ancient Greeks credited with building the foundations of democracy.

"I'm sorry to bring the Greeks into it," Bizos said last week. "But they claim democracy was a Greek invention."

Then he talked about Solon, the ancient leader whose constitutional reforms laid a framework for Athenian governance; Cleisthenes, who introduced more reforms; and Kimon, a statesman who fought the Persians. Bizos, who named a son after the latter luminary, connected the ancients with the present, warning that leaders use conflict as justification for curbing rights.

"The worst enemy of freedom is war and security," he said. Bizos spoke after receiving an award from the Free Market Foundation, a non-profit group that tries to craft solutions to poverty, unemployment and other problems in South Africa.

Bizos, who arrived as a 13-year-old fleeing the Nazi occupation of his country during World War II, considers himself Greek and South African to the core. In the thick of the South African struggle against apartheid, he drew on his roots a continent away. Children in Greece, he said, learn early about freedom.

"We were the slaves of the Ottoman Empire for 380 years," he said. "When you start on grade one about freedom, you get to like it."

He contributed to the transformation of South Africa, which turned from white racist rule to democracy on Mandela's watch. Bizos represented people who defied apartheid's harsh laws, the families of slain anti-apartheid activists, including Steve Biko, and helped write the laws of a new society after the end of apartheid in 1994.

The respected lawyer is credited with getting Mandela to add the words "if needs be" to the 1964 speech from the dock in which he said he was prepared to die for his ideals. The tweak was seen as an escape clause, avoiding any impression that Mandela was goading the court to impose the death penalty.

Last year, some of Mandela's relatives tried to oust Bizos and other directors of two companies whose funds are meant to benefit the family.

Bizos sometimes gets teary when talk turns to Mandela, his old friend, who died in December at age 95. Bizos said some South African leaders have fallen short of their commitments to uphold the ideals of reconciliation and sacrifice associated with the country's first black president.

"The idea that a legacy can be fulfilled to the Nth degree is too optimistic," he said. "But I do believe that we should remind them constantly of what the leader that they praise stood for."

Bizos cited Plato, who warned of tyranny's threat to democracy, and the divine gift of reason mentioned in Sophocles' play, Antigone. Mandela played the role of Creon, an authoritarian ruler, in a prison production of Antigone during apartheid.

In a 2011 speech, Bizos described how he visited Mandela's hotel room on a trip to Greece ahead of the Athens Olympics in 2004.

"The curtains had been drawn. I opened them and said, 'Nelson, come look.' Before us was a breathtaking view of the Parthenon," Bizos said. "He looked and looked and looked and said, 'George, why do I feel like I've been here before?' He couldn't explain it and neither could I. But I like to think that Mandela was simply impressed by all things Greek."