The first time I saw Mr Mandela close up, at a press conference on the morning after his release from prison, I knew that Mr de Klerk would never be in the same league. I wrote in The Independent of 13 February 1990 that "where Mr de Klerk is amiable, clever and urbane, Mr Mandela is charming, wise and has the grandeur of a king"; that while Mr de Klerk had star quality, he belonged to a minor constellation.
Mr de Klerk's finest hour came, not by chance, nine days before Mr Mandela's release. 2 February 1990 is likely to remain etched in South Africans' collective memory for a long time to come as the most significant date in their country's history. That was the day Mr de Klerk gave the speech at the opening of the white parliament that set in train the irreversible course of events that culminated in South Africa's first democratic election on 27 April 1994.
Closing the book on 40 years of apartheid, and 350 years of racist rule, Mr de Klerk unbanned the African National Congress, announced the impending release of Mr Mandela and other political prisoners, and declared that the time for negotiations had begun. None of us knew at the time where the country was headed, or even what the next step would be, but the one thing certain was that the president of white South Africa had crossed his own personal Rubicon and nothing would ever be the same again.
Mr de Klerk himself had his own ideas of what lay ahead. He imagined that he would be able to persuade, or at any rate browbeat, Mr Mandela into accepting something less than one-person one-vote majority rule. He spoke of securing "group rights" for whites - code for a political system in which power would be slanted disproportionately in favour of whites. He seemed to believe, for example, that Mr Mandela might accept a revolving presidency, or equal power-sharing for a period of time. In the end he got a lot less than he bargained for.
The ANC allowed for a one-off deal following the first election whereby each party could have cabinet seats in proportion to the percentage of votes they secured. The National Party picked up 20 per cent of the vote in the 1994 election and four cabinet ministries, plus a junior deputy presidency for Mr de Klerk. But that arrangement did not enhance the National Party's power, it reduced it, and a year later Mr de Klerk announced he was pulling the Nats out of government.
Since then, as it has become increasingly apparent that the ANC will be the party of government for many years to come, both he and his party have been on the wane. Mr de Klerk was wise to leave politics while the memory of his achievement remained fresh.
That achievement, in essence, was to drag along white South Africa - kicking and screaming at times - towards the new democratic dispensation. His co-pilot, Mr Mandela, did much himself to soothe white fears but it was Mr de Klerk who took the bold decision to hold a whites-only referendum in March 1992 to seek approval for the "drastic change" he had promised upon coming to office three years earlier. He ran a vigorous, wholehearted campaign and whites responded with an overwhelming 68.7 per cent "yes" vote.
His words when the result came in matched the immensity of the occasion. "It doesn't happen often that in one generation a nation gets the opportunity to rise above itself. The white electorate has risen above itself... has reached out to all other South Africans."
At moments like these, when Mr de Klerk felt the full weight of his historical responsibility on his shoulders, he would betray a tendency endearingly out of sorts with the dull, lawyerly image he projected to the world. He would shed tears. He wept when he was inaugurated as President in 1989 and he wept again a few months later - I vividly recall the event - at Johannesburg's Jan Smuts airport upon returning from his first European trip. It was the first time in living memory that an Afrikaner leader had been welcomed in the continent from which the Afrikaners had originally arrived. Mr de Klerk, in conveying to a group of waiting supporters his sense of relief and pride and God knows how many other mixed emotions, just broke up, dabbing tears away from his cheeks before he could resume speaking in a normal voice.
Mr Mandela, however, has never felt any personal warmth for Mr de Klerk, despite his numerous politically astute public expressions of camaraderie. This is because he has always felt that Mr de Klerk did not do enough to stop the tidal wave of violence unleashed on the black townships between 1990 and the 1994 election by forces from the old regime hell-bent on somehow stopping the unstoppable. Mr Mandela repeatedly told Mr de Klerk that these forces consisted of an ungodly alliance between Mangosuthu Buthelezi's Inkatha, a child of the old apartheid "homelands" order, and sinister elements within the security forces. But Mr de Klerk would not listen.
One of the prime movers behind the carnage, a security policeman called Eugene de Kock who has since been convicted on multiple murder charges, was awarded a large pay-off by Mr de Klerk's cabinet in 1993. Whether that ill-judged action offers a clue that Mr de Klerk was involved in a cover-up of acts to which he had been content to turn a blind eye is a suspicion that many, including Mr Mandela, have been unable to shake off. Just as likely, though, is the theory that Mr de Klerk was too weak to act against his own security forces and feared that by antagonising them he would be putting at risk the entire negotiating process.
The truth may come out in the memoirs Mr de Klerk says he is planning to write. What we do know, however, is that he did shepherd the transition to democracy with courage and vision, and that when the end came he responded to the decision of the majority with mature responsibility and extraordinary grace.
On 2 May 1994 Mr de Klerk conceded election victory to the ANC in a speech to his supporters at National Party headquarters in Pretoria. Generously acknowledging that he had been defeated by "a man of destiny" who had "walked a long road", Mr de Klerk said that the change in South Africa had been the will of God. "A power greater than man has given South Africa the chance, the spirit to go forward in peace," he said, ending his speech with "God bless South Africa" and then the words "Nkosi Sikelele i'Afrika", the title of the anthem of black liberation.