Breaking with 45 years of apartheid and three centuries of colonial injustice, the constitution starts from the premise that all people, black and white, stand equal before the law. Agreement on an electoral Bill paves the way for general elections on 27 April.
'We are at the end of an era. We are at the beginning of a new era,' declared Mr Mandela, president of the African National Congress, before more than 200 delegates representing 21 parties in the vast hall of Johannesburg's World Trade Centre.
'Together we can build a society free of violence. We can build a society grounded on friendship and our common humanity - a society founded on tolerance . . . Let us join hands and march into the future.'
On a night for grand statements, President de Klerk was not to be outdone. 'South Africa will never be the same again,' he declared. Describing the constitution as 'a contract' between South Africans, he said: 'We have shown that it is possible for people with widely differing views and beliefs to reach basic and sound agreements through compromise.' The document, he said, was 'the distillation of the dreams of generations of disenfranchised South Africans'.
The first paragraph of the 142-page constitutional document set out those dreams, defining the moral and legal foundations of the new order: 'All South Africans will be entitled to a common South African citizenship in a sovereign and democratic constitutional state in which there is equality between men and women and people of all races so that citizens shall be able to enjoy and exercise their fundamental rights and freedoms.'
The constitution, a charter of fundamental rights and the electoral Bill were finally drafted after two years of tortuous negotiations characterised by walk-outs and postponements as well as political violence in the black townships on a scale not seen in South Africa since the Boer War.
The massacres at Boipatong and Bisho, the assassination of Chris Hani and countless other violent incidents contributed to a death toll of 10,000. But the ANC and the government, Mr Mandela and President de Klerk, persisted, guided by the conviction that the only alternative to what has been described as 'the negotiated revolution' was endless war.
Details of the constitution, which will serve as the legal foundation for a five-year coalition government of national unity, were not finalised until late last night, delaying the leaders' summit until 11pm.
Delegates from the 21 parties represented at the Negotiating Council sat through the night at the World Trade Centre, fine-tuning the final document, resuming early yesterday morning. It was drudgery, for the most part, but the failure of the government and the ANC to reach agreement by noon on the manner in which decisions should be taken in the new cabinet brought last-minute anxiety.
Initially the government pressed for a two-thirds cabinet majority, the ANC for a simple majority. The issue was resolved when both sides agreed on a formula whereby decisions will be reached by 'consensus': generally taken to mean that the majority view, certain to be the ANC's after the elections, would prevail.
Before the leaders' plenary finally sat to prepare to sign what they called 'a solemn declaration of commitment to democracy' a further delay was injected into the proceedings when a smiling Mr Mandela insisted on doing a tour of the chamber to shake hands with the leaders of all 21 parties.
In terms of the fundamental objectives Mr Mandela, 75, set himself when he embarked on the liberation struggle half a century ago, he had much to smile about. 'Millions of those who were not allowed to vote will do so', he declared. 'I, too, for the first time in my short life will vote.'
What he will vote for will be a new 400-member parliament which will sit in Cape Town, as now, and will be elected on the basis of proportional representation. The coalition cabinet over which he will in all certainty preside will include two vice-presidents, one of whom will probably be Mr de Klerk.
The new president will be commander-in-chief of the armed forces. Their stated loyalty to him and to the new order might be tested soon.
The right-wing Freedom Alliance, whose five parties walked out of the constitutional talks in July, has threatened to sabotage the April elections.
Key points of the agreement
Elections next year for coalition government to run for five years
Interim constitution in force for same period
President and two vice-presidents appointed by parties getting more than 20 per cent of vote
Cabinet appointed by parties with more than 5 per cent of vote
400-seat national assembly and 90-seat senate elected by proportional representation will adopt final constitution
Nine new provinces with own legislatures
A constitutional court will mediate between centre and provices
Bill of Rights to protect individuals from any discrimination
Historic bargain. . . . . . .14
Five years to build. . . .15
Leading article. . . . . . . .19