For the last 20 years, centre-left political parties everywhere have engaged in various exercises of revision and repositioning. All have failed. Significantly, Tony Blair's New Labour, electorally the most successful, triumphed only after changing its supposed ideology and even its name.
Perhaps more significantly still, parties across the entire spectrum of the left have been unable to find either a plausible or a coherent response to the world financial crisis. But that is a consequence, not the cause, of their failure to redefine themselves.
Can we find clues to their travails in Kevin Rafter's story of Democratic Left, which in its brief lifetime changed its name, not once but half a dozen times, and changed its shape as often?
The only honest answer is "not really". The more one ploughs through the minute details in this book, the more one realises that Democratic Left was totally untypical, in differing ways, of both Irish politics and European politics.
One has to start with origins. These were recounted two years ago in The Lost Revolution, by Brian Hanley and Scott Millar. That book gave much innocent amusement to people who found it confirmed that model citizens had been members of the Official IRA and its predecessor, in some cases for 20 years. Some of the same people joined the valiant struggle to break the connection with violence and illegality and bring the organisation, under the title the Workers' Party, into the democratic mainstream.
But as one dubious connection diminished, another grew.
As Rafter notes, and he is not alone, former Democratic Left people are reluctant to this day to admit that such an organisation as the Official IRA ever existed. They are equally shy on the Workers' Party connections with the Soviet Union and, bizarrely, North Korea.
Indeed, Rafter is a little coy himself. Nowhere in this book does the word "Stalinism" appear. He uses the phrase "democratic centralism", relating to the party's internal affairs, without apparent irony. He could have quoted the definition once offered by a leading member: "Democratic centralism means that you bleedin' do what I bleedin' say."
Just about the time the Berlin Wall fell, this state of affairs became intolerable for the parliamentary party. (It will be fascinating to see if and how a similar process plays out in Sinn Fein.) The inevitable split followed. But it remained for Democratic Left to gain the ultimate symbol of respectability, acceptance into a coalition government.
Key to this process was the seemingly unlikely figure of John Bruton, who accepted that the minor party had put its questionable past behind it. In 1992, he thought coalition with Democratic Left a step too far for "the Fine Gael base". In 1994, in different parliamentary circumstances, he formed the Rainbow Coalition, in which he developed a most remarkable relationship with Proinsias De Rossa.
But De Rossa and Democratic Left's junior ministers got little credit for their competence, and after the Rainbow lost the 1997 General Election they were left high and dry. They soon concluded that amalgamation with Labour was the only option.
For all the jokes about "reverse takeovers", it took place on Labour's terms in January 1999. A "bonding" process followed, sometimes bumpy. Some Labour members were slow to forgive Democratic Left members for their past associations, others had felt the sharp end of Democratic Left tongues from time to time. But soon enough the marriage came to seem the most natural thing in the world.
And after all that, what is the legacy for Labour and the political system in general?
Clearly, at least two former Democratic Left luminaries, Eamon Gilmore and Pat Rabbitte, may still have important roles to fill. Aside from that, it has had no more influence on the left than, say, the Progressive Democrats on the right.
The Irish political system is singularly unfriendly to ideology of any kind: one might almost say, unfriendly to sustained thought of any kind, especially the revisionist kind.
Good luck to the next bunch of brave warriors, of left or right, who try to engage in it.