Roosevelt, Stalin, Churchill, Hitler — these were the names that, for much of the world, defined the first half of the 20th century, the most destructive era in history.

Gandhi, King, Mandela — these, it could be argued, are the figures who will live longest in the public consciousness as we look back on the postwar world: leaders who had no real armies to speak of and who wielded little power in office but who helped create a new ethic through the power of their ideas and the example of their lives.

Mohandas Gandhi and Martin Luther King Jr. were, of course, men of peace, preaching nonviolent resistance to oppression and exploitation. Nelson Mandela, though not a combative man, felt there was no alternative to war against the apartheid government under which he lived, and he spent 27 years in prison for plotting violence against that government. (He and his associates planned a campaign of nonlethal sabotage and envisioned a military front, neither of which had come to much before he was arrested.)

Mr. Mandela emerged from prison in 1990 with greater stature than any leader in South Africa, white or black. More important, he came out espousing reconciliation, understanding and forgiveness. Although he was an old man by the time he took power in his country, and delegated much of the work of governing to others, the trust he had gained among people in just about every camp was essential in South Africa’s transition from a racial dictatorship to a true democracy.

Like Gandhi and King, Nelson Mandela had personal shortcomings, domestic discord and so on. But it was, to a large degree, the overwhelming and reassuring force of his personality that won over nearly everyone he came in contact with, from African villagers to prison guards to the men who ran his government. He was a regal figure, born into tribal royalty, tall, handsome and charming. He moved comfortably and confidently among his country’s many peoples — black, Indian, white — and made a point of seeing the good in each of them. As one of his admirers remarked, he had the gift of making all those he met feel better about themselves.

Also as with Gandhi and King, Mr. Mandela engaged in one of the world’s most vital postwar tasks: dismantling the strong web of racist ideas, with which certain Western thinkers had sought for more than a century to rationalize the subjugation of others through colonialism, segregation and disenfranchisement. Anyone born in the past 50 years or so would have a hard time understanding how pervasive these ideas were in many advanced and sophisticated nations (including our own, which in much of its territory bore an unsettling resemblance to apartheid South Africa).

Mr. Mandela, who died Thursday night at age 95, seemed to understand that the motivating force behind ethnic, religious and racial hatred is not only, or even primarily, self-interest; it is fear, distrust, a lack of understanding. In his person and his policies, he set out to show those on the other side that they had little to fear. He sought unity rather than revenge, honesty and understanding rather than the naked exercise of power. These are all fine abstractions, of course, but never so clear to us as when there is a living figure to exemplify them. That's why Mr. Mandela’s influence extended so far beyond South Africa and was felt by so many of the world's peoples other than Africans. It is the reason, now that he is gone, that it is more important than ever — in a century marked so far by frightening eruptions of terror and religious intolerance — to keep before the world the name and example of Nelson Mandela.

Read more on Nelson Mandela:

Paul Taylor: Mandela knew how to use the moral high ground

Richard Cohen: Mandela’s standard for us all

Michael Gerson: He steered South Africa from the abyss

Steven Mufson: His letters from prison built a new South Africa

The Washington Post’s Sudarsan Raghavan talks about the life and legacy of Nelson Mandela. (Thomas LeGro/The Washington Post)