So when he was asked by reporters in the United States, where he is now on a visit, what he thought of right-wing demands for an independent Afrikaner 'homeland', he flatly ruled out demarcating a piece of South African territory along ethnic lines.
Faithful a reflection of ANC policy as this was, its timing was unfortunate: it gave hardliners on the right wing a pretext to pull out of talks with the ANC.
After it had been revealed in a joint statement last Friday that the ANC had been negotiating secretly with the Afrikaner Volksfront (AVF), an umbrella right-wing body headed by retired army general Constand Viljoen, the ANC told its officials not to make any further comments. Evidently the message did not cross the Atlantic.
On Wednesday, the AVF announced withhdrawal from all bilateral contacts with the ANC and the government of F W de Klerk. A statement by General Viljoen and the parliamentary Conservative Party leader, Ferdi Hartzenberg, said Mr Mandela had made it plain in the US that he did not accept Afrikaners' right to self-determination.
The statement also shed some light on the friction widely known to exist between the AVF's two most senior figures. Last week Mr Hartzenberg spoke repeatedly in parliament of war. Simultaneously, in speeches at right-wing meetings, General Viljoen was scolding those who, not knowing war as he did, advocated it. He had met Mr Mandela, he explained, and then held a number of meetings with the ANC's national chairman, Thabo Mbeki, to try and avoid a bloodbath.
Mangosuthu Buthelezi, the leader of the Inkatha Freedom Party, is another right-wing leader the ANC is trying through bilateral meetings to woo back into the democratic fold. Mr Mbeki, undoubtedly the smoothest political operator in the ANC, has again been the man assigned to this delicate task.
He will not have been pleased to learn that in another excess of honesty during a press conference in New York, Mr Mandela contrasted Gen Viljoen, 'a responsible man', with the notoriously hyper-sensitive Zulu chief, who he said was 'in danger of being hopelessly isolated'.