It will hardly get a look in, what with the Larne and Howth centenaries, and the first World War, and course the Clontarf millennium. But this year also sees another important anniversary, a term for which may not even exist. “Millenniosesquarcentennial” is my best guess.

Yes, it will be 1,350 years this summer – doesn’t time fly? – since the Great Plague of AD 664. And yet, frustratingly, hard information about the event remains as scarce as ever. We still don’t even know, for example, what kind of plague it was.

Smallpox or yellow fever seems likely. But there’s also an argument for bubonic, even though it’s not clear whether Ireland had a rat population then (witness the notorious fact that the first official language uses the same word for “rat” and “Frenchman”, due to those two species’ apparently coincidental arrival here circa the Norman invasion).

We do know that the disaster struck on both sides of the Irish Sea. And that, in Bede’s account, “many of the nobility, and of the lower ranks of the English nation” died of it here too, because they were in Ireland as part of the famous free education scheme then available in the Land of Saints and Scholars.

Irish monasticism was the toast of Europe at the time, although one story of the plague reflects less well on the nation’s holy men. It may be an unfounded libel, for all I know. But it’s entertaining, and they can’t sue now, so here goes.

In short, it suggests the calamity was man-made, or at least man-ordered: ie that in response to a plea from Ireland’s high kings, some leading monks prayed for a plague on the lower orders, to relieve pressure on food supplies.

In our more enlightened 21st century, when the high kings relieve pressure on resources merely by sending the surplus population to America for a few years, this seems hard to credit. But if the monks did facilitate this drastic austerity plan, it was a kamikaze mission, because many of them died too.

The plague may in any case have had lasting politico-religious consequences, thanks to the Synod of Whitby, also held in 664. Whitby was an attempt to resolve differences between Rome and the “Celtic” Christians, including their competing calculations of Easter. Whether the local calamity influenced the outcome, Roman orthodoxy triumphed.

Either way, post-plague, Ireland remained both saintly and scholastic for several more centuries, although the mid-600s were probably the peak of that phenomenon. And this, by the way, poses a very interesting question about religious authority.

The saints for which this island was then renowned were not, of course, officially canonised in Rome. That whole process evolved later. In the first millennium AD, throughout Europe, holy men and women and nuns were elevated to sainthood by mere popular acclaim.

Ireland just happened to have more of them than anywhere else. There were many hundreds, at least, mostly now forgotten, although their names still often survive in toponymy.

Wherever you see an Irish place-name starting with “Cill” (church) or “Tigh” (house), or even sometimes – confusingly – “Coill” (wood, which used to have religious associations), you can bet there’s a local saint’s name attached.

But in the second millennium, the canonisation system was regularised. From then on, Rome imposed quasi-legal criteria. Ireland, meanwhile, continued to be devoutly Christian and, post-reformation, staunchly Catholic. So how many officially-recognised saints has it to show for all that Vatican-centred piety?

A miserable four, in fact. There’s St Malachy, who died in 1148; St Lawrence O’Toole (1180); St Oliver Plunkett (1681); and St Charles of Mount Argus (1893). And that’s it. It would seem a poor record, by any standards. But when you consider that the fourth of the quartet – the only official Irish saint to have lived in the last 300 years – was born a Dutchman, it’s almost an insult.

There are only two possible conclusions. Either the centuries of Irish fidelity to Rome were cruelly unreciprocated, with many candidates worthy of sainthood overlooked. Or else it’s the earlier era that was the aberration.

If I may play Devil’s Advocate on that distant time now, I can’t help noting that, with disturbing resonance, it featured a building boom: of churches and monasteries, mainly, and later of sky-scraping round towers. But perhaps the similarities didn’t end there.

Could it be that all those sanctified monks were themselves the products of a bubble? That the market had been infected by irrational exuberance? And that the countless saintly place-names still dotting the country today were products, like the ghost estates since built on them, of an era of light regulation?

I look forward to hearing answers at the Plague of 664 Summer School.

fmcnally@irishtimes.com