Had any other party or coalition held power in this State in the autumn of 1969 they, like Fianna Fail, would have been under pressure from their own supporters, from the public at large and from Northern nationalists.
And senior members of Fine Gael and Labour have privately admitted that, under pressure, they, too, would have been divided in their attempt to devise an appropriate response.
What was different about Fianna Fail was the depth and intensity of its divisions. FF factions which disagreed on leadership, political standards and the national question had been active since 1966.
There were, on one side, two of the most powerful leaders in the State, Neil Blaney and Charles Haughey, and on the other Jack Lynch - Tom Garvin's "very unfanatical politician" - and his unfanatical allies: George Colley had called attention to low standards in high places; Paddy Hillery was to challenge the militants at a critical ardfheis; Erskine Childers had been one of the first to break the clotted bonds of Civil War.
Sooner or later everyone, North and South, would be caught in their struggle for control of the party. For, as with monolithic unionism, control of the party was equated by would-be leaders with control of the State. It was the natural order.
Eamon de Valera and Sean Lemass were not only the makers of policy, they personified the national movement. They breathed the spirit of the party and never for a moment doubted that this was the spirit of the nation.
The Arms Crisis ended old certainties about the national question and the authority of leadership. But already the party had begun to change in other ways, though even commentators tend to forget the influence of the fund-raisers of Taca and how quickly, in the world in which Haughey and Blaney flexed their muscles, they came to be accepted as part of politics.
I remember vividly an ardfheis in the 1960s at which the delegates seemed determined to put an end to the connection with what most of them would have called high finance.
When Blaney rose to speak the men in the open-necked shirts (as they still were) viewed him with resentment. For a whole, sweating hour he worked on the hall, persuading row after row that if they didn't appeal to business others would. High finance would serve other political interests, not theirs. And future generations would blame them for it.
But it was Haughey, not Blaney, who stayed with the party after the Arms Crisis; it was Haughey who became leader and continued the fight against those who argued for modernisation - on the North, on social issues, in party organisation and in FF's approach to the wider world.
It was Haughey who had Des O'Malley expelled - for conduct unbecoming - and made life so uncomfortable for Mary Harney that she left to join O'Malley in founding the Progressive Democrats.
It was Haughey who, because he wanted and needed to stay in office, broke another taboo (he had already broken the one on leadership) and entered coalition with the Progressive Democrats.
It was O'Malley who forced Haughey to turn on one set of friends by setting up the beef tribunal and on another by insisting on Brian Lenihan's dismissal. O'Malley was a powerful influence on the establishment of tribunals to examine payments to politicians, Haughey included.
Now, we hear his critics argue for a strictly limited inquiry into the changing of Col Michael Hefferon's statement during the Arms Trial, when an inquiry which included Public Accounts Committee hearings (public and private) and State papers would make more sense.
And, as we listen to familiar voices reaching conclusions about who did what and why, it doesn't take a great imagination to conclude that what many are after is "vingeance bejasus" as a famous secretary of Sinn Fein once said when asked what the party stood for.
These are familiar voices once regularly heard insisting that it would be wrong to jump to conclusions in Haughey's or Burke's or Lawlor's cases. And "mind you, I've said nothing" wait for the revelations about the other crowd.
It makes for an intriguing dilemma for the Government as Ahern and Harney decide the future of Campus Ireland and what to do about disciplining the judiciary.
But, before they start crowing, the Opposition ought to explain their acceptance of what amounts to another tax amnesty.