The archive is meant to show Nelson Mandela as a person rather than an icon
Unseen writings of Nelson Mandela which are being sold this week show the anti-apartheid leader at his most candid.
The former South African president's archive shows him chiding himself over a "grave error of judgement" when he proposed lowering the voting age to 14.
He also talks about how he was "not a very bright student" at university.
The Nelson Mandela Foundation (NMF) is selling the rights to the 100,000-word archive of notes, diaries and letters at the Frankfurt Book Fair.
On his way to becoming South African president in 1994, it is hard to think that Mr Mandela put a foot wrong.
But the NMF's Verne Harris told the BBC the compilation, called Conversations With Myself, showed Mr Mandela "not as a saint or an icon, but as a person".
The compilation of notebooks, diaries and notes from speeches and meetings contains scanned-in documents from Mr Mandela's life stretching back to 1929, when he was 11 years old.
"This resource is really a window into Nelson Mandela reflecting, he is not communicating to a particular audience it is him laying out his personal thoughts," Mr Harris said.
Jonny Geller, of the Curtis Brown literary agency, has taken the archive to display at the Frankfurt Book Fair.
He says he has never seen a collection like it.
"I've never heard of a living political leader giving up their entire archive," he said.
"I can't think of any other political leader who has opened up their archive without any censorship."
Examples of the candid insights include notes from a meeting during the 1994 election campaign, a few days after he had proposed lowering the voting age.
"He was in a meeting with members of the ANC [African National Congress]," said Mr Harris.
"We see him writing down what everyone is saying - basically attacking him for what he said.
"He made an entry in the notebook where he said: 'I have made a grave error of judgement.'
"That is the man the world needs to know, a man who admitted his mistakes and reflected on them."
Mr Harris cited another extract from an interview when Mr Mandela is asked about his poor academic record when he was a law student.
The interviewer says: "You didn't do well in your legal studies at Wits university, is this because you had a racist lecturer?"
Mr Mandela replies: "Yes I did have a racist lecturer, but that is not why I didn't do well."
Later in the interview, he comments: "I was not a very bright student, I failed all of my subjects at Wits. I had to go to prison in order to learn how to be a good student."
The royalties are to be divided between Mr Mandela and the Nelson Mandela Foundation.
Mr Mandela has already written a two-volume autobiography and authorised at least one other biography.
Among numerous other books about the former leader, there are collections of his speeches and many books charting his impact on global politics.