The release of State papers each year usually triggers a plethora of fascinating stories about life as it was 30, 40 or 50 years ago.
What it should also do is to remind us of our utter inability to understand even the relatively recent past.
Take, for example, the revelation that President Douglas Hyde sent his secretary to the German envoy in Dublin to offer his condolences upon the death of Herr Hitler in that unfortunate incident in Berlin. The presidential protocol records: "No message of sympathy sent as the capital of Germany, Berlin, was under siege, and no successor had been appointed. Decision was not to send the President to the funeral or to send a wreath for a tomb or grave. No religious service to be held."
Let me give you that again: "Decision was not to send the President to the funeral. . ." This is so surreal that it is quite impossible for us today to connect at any point with the mind of someone who could write it. It is rather like the protocol book of the President of Malawi soberly and seriously noting that a decision had been taken not to send him on a state visit to Saturn's rings, and that there were no plans - for the moment anyway - for him to go on a tour of the hulk of the Titanic.
In other words, the mind of 1945 is one we simply do not and cannot understand. That being the case, we should not rush to judge it; for we have no common rules, no shared common sense or understanding of the real, the possible. But we do not have to go back 60 years to find that mentalities alter so totally that individuals themselves can no longer remember how they felt, or could explain those feelings.
What person who defended the criminalisation of male homosexual acts in the 1970s and 1980s would justify it today? Could those who agreed with the State's prohibition of condoms repeat their arguments in 2006, and really believe them? Yet those bans were part of the political consensus which crossed party lines, and which apparently appealed to the majority of the Irish people, who, as a matter of passionate conscience, would not let other Irish people follow their own consciences.
This today is quite astounding, and utterly incomprehensible: for of all intellectual faculties, conscience is the most dependent on contemporary ethos - and once lost, is perhaps also the most irrecoverable. Thus in 1975, the Department of Foreign Affairs was anxiously monitoring the campaigns of US journalists who were criticising repressive Irish policies on homosexuals and condoms; who could have imagined then that, 30 years later, condoms would be on sale on supermarket counters, homosexual unions would soon be recognised by the State, and women would unashamedly be buying vibrators over open counters in a large department store in O'Connell Street?
Thus L.P. Hartley's oft-quoted opening line in The Go-Between - "The past is another country: they do things differently there" - now misses the point. Because you can go another country, learn its ways, its language, its habits, its ethos, its taboos. But the past is kept remote by an impenetrable force-field of time. We see merely vague spectres, as through a glass darkly. That force-field prevents us even remembering or understanding our own thoughts, motives, desires.
And as for those of other people - such as Liam Cosgrave when he voted against his own Bill to permit contraceptives to married couples in the 1970s, or those government officials who in 1945 actually discussed whether or not old Douglas Hyde should attend Hitler's funeral - why, these are utterly inexplicable phenomena. We are as able to empathise with the motives and the instincts of these decent, honourable men as we are with a herd of migrating wildebeest.
For as we learn, we forget what we knew. More to the point, we even forget that we knew. We re-create ignorance from a landscape of what was knowledge, vindicating Donald Rumsfeld's extremely shrewd observations on the nature of knowledge, (though much-mocked by fools): "Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns - the ones we don't know we don't know."
So in addition to the unknown unknowns - the tsunami leaping from its seabed, the aircraft flying into the Twin Towers - we also have the forgotten knowns. We have the once-knowns that we know we no longer know, and more deadly still, the once-knowns we no longer know that we once knew.
I know that I once knew the Latin Mass by heart, and do so no longer; but this is a deficiency I can repair. However, I can do nothing whatever about that all-destructive ignorance which has concealed even the deed of forgetting.
Done to scale, this is how civilisations die. This is how the consciously Irish, Catholic civilisation which infused this country long before the State was founded, and went into the making of the laws and the culture of post-independence Ireland, has suddenly begun to perish. There is clear continuity between 1945 and 1975, but very little indeed between 1975 and today. And by 2035, there will be none whatever between that future Ireland and the 20th century Irish State from which it grew.