Dead men do tell tales if you wait long enough
The problem with Northern Ireland history is that you have to wait until most of the main players are dead in order to hear the truth.
The Boston College archive, where paramilitary members leave their testimonies to be published posthumously, is one example.
The confirmation of long-denied links between the African National Congress (ANC) and the IRA in Kader Asmal's recent memoir is another.
Unlike the ANC in South Africa, the IRA did not emerge victorious, or achieve an amnesty for its members, who can still be jailed.
In that sense, the war is not over and, as Winston Churchill put it, "in wartime, truth is so precious that she should always be attended by a bodyguard of lies."
That is why Mr Asmal described the accusation of ANC-IRA links as "tendentious" in 2002. Then, Michael O'Riordan, the former general secretary of the Communist Party of Ireland (CPI), who acted as a go-between and died in 2006, was still alive.
Now the full story - or at least more of it - is told by Mr Asmal in his book Politics in the Blood.
He tells how, as a 1970s exile from the apartheid regime working as a law professor in Dublin, he took on a delicate mission for the ANC.
Umkhonto we Sizwe (Spear of the Nation, or MK) - the ANC's military wing - wanted IRA training for some of its members. Just why this should be necessary is intriguing.
MK was supported by many states.
It had bases in Angola where the friendly MPLA government facilitated cooperation from African, Cuban and east European armed forces.
MK may have felt that the IRA had developed more expertise in sabotage and underground operations than had conventional armies. Asmal didn't ask questions and, confiding only in his wife, Louise, approached Mr O'Riordan - a former IRA member who he considered "a man of great integrity".
He tells us that Mr O'Riordan set it all up with Gerry Adams and, after one mix-up, the MK militants were sent for two weeks' training in Ireland.
Later, IRA members went to South Africa and did the reconnaissance for an MK bombing of the Sasolburg oil refinery - a seminal attack in propaganda terms.
It was kept tight. Shawn Slovo, whose father Joe was an MK leader, made a film called Catch a Fire about it and never mentioned the IRA's role. The three MK cadres involved in the attack appeared before the South African Truth and Reconciliation Commission and Ireland didn't feature in their account, either.
In theory, Gerry Adams could be in trouble even now, but it is hardly likely.
No one died in the attack and the ANC is a popular cause.
In any case, Mr Asmal and Mr O'Riordan - the only people who could give evidence - are both dead.
It is a pity, though, that we so often have to wait until everyone is dead to hear the truth.
Bringing it out a little sooner is a challenge which the Assembly and the Northern Ireland Office should find ways of meeting.