After a triumphal state visit to Britain and France that would have tested the stamina of a 20-year-old, President Nelson Mandela returned home last week in time to celebrate his 78th birthday. Joyous as that occasion was, it also served as a painful reminder to South Africans of all races that the man who personifies reconciliation in their country will not be around much longer to lead them. Although it has been no secret in South Africa that Mandela will step down at the end of his presidential term in 1999, it was during his British visit that Mandela publicly confirmed his intention to retire that year. "I'll be 81 by then," he told journalists in London, adding that he didn't think it wise for a robust country like South Africa to continue to be led by one who was already a septuagenarian.

Mandela's latest tour in fact was seen by some analysts as his way of reassuring the international community that there will be leadership and stability in South Africa after he is gone and of selling the idea that the succession is in good hands. While in London he made it clear that Deputy President Thabo Mbeki will succeed him as head of the African National Congress and privately indicated that he expects Mbeki to take over as head of state.

But the conservative world of international business and finance may take some convincing that there can be a smooth transition to a post-Mandela era. One reason the South African rand plummeted earlier this year was a rumor that the leader's health was not good. It was started, some say, when a London stockbroker heard a South African colleague on the telephone saying "Nelson's sick." He was actually saying "Yeltsin's sick," but the damage was done. The rand fell 20% against the U.S. dollar and has never recovered from continued market jitters caused by fears of political, economic and social instability.

Mandela is not sick and indeed is one of the fittest 78-year-olds around. But the truth is that he is starting to ease himself out of the day-to-day running of his country, having become, by his own admission, "more a decoration than an asset," and is publicly beginning to muse about a future when he can relax on his Transkei farm and leave the affairs of state to "younger men who can move and shake this country." These days he rarely chairs Cabinet meetings and is satisfied to "lead from the rear," says political scientist Robert Schrire, who adds, "He now seems to be running out of steam quite rapidly as a leader and manager."

A President who modestly defines his role as a chairman of the board, Nelson Mandela is a victim not only of his dramatic role in South Africa's historic trek toward democracy and reconciliation but also of his own extraordinary personality. He has natural dignity and grace, which turn wrath into calm and make followers out of foes. South Africans of all races call him by the reverential tribal name Madiba. But while the Mandela factor has been useful in placing the emergent South African democracy on the global agenda, says Schrire in an analysis in Natal University's Indicator magazine, "it has been destructive in creating mass fears of life without Madiba."

Can Mbeki carry the magic of Madiba into the millennium? Clearly Mandela believes so. After Cyril Ramaphosa, the chief constitutional negotiator for the A.N.C. and a possible contender for President, dropped out of politics to go into private business earlier this year, the suave, pipe-smoking 54-year-old Mbeki was left as the only obvious choice. Mbeki, the son of an A.N.C. and Communist Party stalwart, has been virtually groomed to be a successor to Mandela. An economist who learned diplomatic skills as right-hand man to former A.N.C. president Oliver Tambo, Mbeki is gathering power. As Deputy President he functions as an unofficial Prime Minister, chairing Cabinet meetings. He is also regarded as a de facto Foreign Minister and the government's best negotiator with the conservative, white right wing as well as the white-dominated business community.

Mbeki has been criticized for not being decisive enough in handling some of the A.N.C.'s internal problems, and abroad he has been accused of virtual appeasement toward Nigeria's military regime, particularly because he was tardy in condemning the execution last year of environmental activist Ken Saro-Wiwa. But last week he was being hailed as having played a key role in promoting a peace initiative between the A.N.C. and the Zulu-based Inkatha Freedom Party that could finally end the long-standing violent conflict in KwaZulu-Natal. In the A.N.C. it is fairly well established that the decks have been cleared for Mbeki. At next year's party congress Mandela will probably hand over the leadership to Mbeki, thereby endorsing him as President-designate. Then South Africans--and the adoring world--will be seeing less of Madiba and more of the man who will assume the leader's mantle. It will be a tough act to follow.