When Nelson Mandela was imprisoned on Robben Island by South Africa’s apartheid government, the cruelest punishment was not the backbreaking quarry work, the damp eight-foot-by-seven-foot concrete cell in which he was confined, or even the cold straw mat he was made to sleep on for 18 years.

More terrible than that, the regime tried to stifle Mandela’s mind and his meaning to the world. He was permitted one 20-minute visit each year. He was permitted one letter every six months. He was often locked in solitary confinement for possessing forbidden news clippings. His source of inspiration was a smuggled book, the “Complete Works of Shakespeare.”

Mandela signed his name beside a passage from the play Julius Caesar: “Cowards die many times before their deaths / The valiant never taste of death but once.”

When Mandela did die on December 5, he exited the world valiantly as the leader of the eventually triumphant anti-apartheid movement, the patriarch and first black president of modern South Africa, and a champion of conciliation whose Truth and Reconciliation Committee began the process of healing a divided country rather than letting it fracture.

But Mandela’s work in South Africa is far from over. The African National Congress party did not transition well from successful activist movement to governing political party. Mandela’s succeeding leaders, Presidents Thabo Mbeki and Jacob Zuma, have been far from his equals. The incumbent President Zuma has been embroiled in long legal battles over corruption, racketeering, and rape.

The wealth gap between white and black South Africans has persisted since the end of apartheid—a symptom of weak leadership from the ANC. The same ANC’s hesitation in combating AIDS early on led to one of the worst epidemics in the world. South Africa remains a nation of immense potential mired in a seemingly inescapable muddle of corruption, inequality, and disease.

Yet although South Africa, and indeed the world, has much progress to make after Mandela’s death, that does not diminish the man’s legacy. At his memorial, attended by 91 heads of state, Mandela shared the unwavering admiration of world leaders often at odds with one another. President Obama’s handshake with Cuban President Raul Castro drew criticism—but it fit the conciliatory spirit of a man who invited his prison guard to the front row of his presidential inauguration.

During the Rivonia Trial that led to his imprisonment, Mandela said, “I have cherished the ideal of a democratic and free society in which all persons live together in harmony and with equal opportunities. If need be, it is an ideal for which I am prepared to die.”

It should be an ideal with which all of us are prepared to live.