It was touted as the book of last week's Frankfurt Book Fair, the hottest property around.

That it is a book not yet assembled did not deter almost every major book-publishing territory from bidding for Conversations with Myself, which will be drawn from Nelson Mandela's private archives, embracing half a century of diaries, letters and personal notes not seen before.

Sixty percent of the proceeds will go to Mandela and 40% to the Nelson Mandela Foundation (NMF), to which Mandela has entrusted his papers. If the six million estimated global sales of Mandela's 1994 autobiography, Long Walk to Freedom, are a pointer, Conversations with Myself ought to be a tidy earner.

At a "select auction" in London, just before Frankfurt, Pan Macmillan won British publication rights for what is described only as a "significant" sum. Macmillan's United States imprint, Farrar Straus & Giroux, has acquired US rights; deals are in place for Portugal, France and Denmark; offers are in from Germany, Israel and Italy; and auctions will follow in Brazil, Sweden and the Netherlands.

Contracts will be finalised after approval by the NMF and its partner in the project, New Zealand-based book-concept packager PQ Blackwell, which meet in Johannesburg on October 22 and 23 to discuss the bids.

Set for publication towards Christmas 2010, the book is projected to run to 100 000 words, with introductory notes by Mandela and thematic sections inspired by Mandela's lessons from life and illustrating his wisdom. Mandela's archivist, Verne Harris, and Professor Tim Couzens will lead the editorial team.

Spectacular though it is as a publishing story, Conversations with Myself must be seen in the more enduring and wider context of the publication programme of the NMF's Centre for Memory and Dialogue.

Harris -- who heads the Memory Programme at the centre, as well as being acting head of the NMF -- points to its archival publication series, inaugurated by A Prisoner in the Garden, a selection from Mandela's prison archive.

Conversations with Myself, says Harris, "signals the existence of Madiba's private papers and begins the process of putting them into the public domain".

The third book will be a selection of Mandela's prison letters.

Mandela has described his archives as containing "traces of my life and those who have lived it with me". Harris says that Mandela gave his personal mandate to archivists "to do what you need to do".

"Nelson Mandela has privileged memory as a resource," says Harris, and the NMF is intent on making Mandela's own recollections as widely available as possible.

It has targeted young South Africans with the comic-book biography of Mandela, distributing one million copies free, and the recently published children's picture-book version of Long Walk to Freedom.

There are discussions with Google to digitise the Mandela archives, making them globally available in full. Putting Mandela's private papers into the public domain, initially with the selection in Conversations with Myself and most ambitiously on the internet, invites "serious, scholarly, critical analysis" of Mandela, says Harris.

This would be significant for Mandela's heritage, which could do with fewer biographies drawing on the same sources. In delving into the archives future Mandela biographers have nothing to lose but the chains of hagiography. They have a world to win.