The stuff I’m drinking, an iodine-scented tincture called Caol Ila, was distilled in July 1977 and bottled this summer. It makes sense to drink it at 17 because that’s when, for reasons that aren’t scientifically quantifiable, it puts on the full parade of flavours. Experts, for the record, say it tastes like mown grass or gorse blossom. The less committed always want a squint at the bottle; once their eyes stop watering, that is. One thing always bothers them, apart from how to say “kale eela” (as near as dammit) is: why 17 year old? This concern takes a variety of forms. “Wouldn’t it be better if they left it for the full 20?” Well, actually, no. “I suppose it’s much better than the 12 year old.” Different, certainly, but otherwise, no again. And then, even more bizarrely, “Was July 1977 a special time in your life?” or (once) “Did your father ‘lay it down’ for you when you graduated?” That’s one more big no and one leave it out, mate.

My father clung to a little-known medical theory that stated it was physiologically impossible to appreciate malt whisky before the age of 30, jazz after the age of 40, and The Dream of Gerontius before the age of 50. Strict application of this theory also meant that while whisky (the cooking sort) could be spooned down my throat for bugs and blains between the ages of nought and about 11, a half of lager was deemed to be intensely toxic between the ages of 11 and 21. He had the law, of course, pretty much on his side, mathematically speaking. The law likes to do it by numbers, too, though as I always used to point out, the law had settled on 18 as the date on which the harmful impact of Tennent’s suddenly abated. The principle holds, though: X marks the electoral spot at 18, when the spots are still pretty rampant; grey Cortina at 17; wheelies on a Kawasaki at 16; also sex, if doing wheelies palls; home alone at 14.

More generally, the culture itself is obsessed by numerology. Now that learning history as a procession of dates has been laughed out of court, in all but the wilder reaches of conservative educational thought, history as the average citizen is encouraged to perceive it has become a sequence of time capsules, to be dug up on some appointed date or, if you prefer consistency in your analogies, casks to be tapped at the end of a fixed term. That, essentially, is how literary and musical history are promoted; less so art history, though fashion prevails even there, since pictures and sculptures have an inbuilt permanence and fixity, and don’t need to be reread or revived in performance in quite the same way.

Biography, which in one form or another constitutes a substantial tranche of any year’s non-fiction books and a hefty proportion of major newspaper and broadcast documentaries, is perhaps the most simply quantifiable way of determining how a culture perceives itself. Scan a list of the year’s published biographies and you’ll find a certain numerological consistency. “In X’s centenary year”, “fifty years after the death of Y”, “Z would have been 75 this month”. Read the prefaces and you’ll come across elaborate methodological and theoretical contortions which purport to explain why now is a good time to be mugging up on Sir Henry Wood (died 1944) or Robert Louis Stevenson (died 1894) or Philip Hesltine“Peter Warlock” (born 1894). Very few authors are inclined to come clean and add to the list of positive justifications “because my editor asked me to”. Few editors would admit they got the detail off a list produced by the research department, or that cultural anniversaries, like the increasingly pricey hierarchy of nuptial remembrances (cotton to platinum, if I remember rightly, though a musician friend once claimed that his parents were celebrating their plutonium anniversary with a bottle of champagne and a fistfight) are completely arbitrary and intrinsically meaningless.

The odd diminuendo of the Stevenson centenary was explained away by one editor recently, who said “Death anniversaries are always less important than birth ones”. The truth is that Stevenson had already been adequately tapped and tasted, in the 1970s, when the advocacy of fabulists like Jorge Luis Borges promoted him from the second division of “juvenile authors” to the premier league of proto-Post-Modernists.

By 1994, RLS had started to lose some of that distinctive tang and the celebrations, and the string of books that marked them, had the oddly inappropriate look of fresh flowers on an old grave. Similarly, Aldous Huxley, who’d already proved how capricious an old bitch posterity was by dying on the same day as John Kennedy and thus being denied much in the way of obituary space. In 1994, readers primed to believe that this was going to be a “big Huxley year” were inclined to find him doubly passe, first as an observer of a social nexus we’re no longer much interested in, and then as a prophet of technological, environmental and even pharmacological futures. Cometh the year, cometh the slight anti-climax.

Ideally, anniversaries are, if you like (and will forgive yet another analogy), the spark plugs of a strong critical culture. Editors prefer to call them “pegs”, and the difference between the polite fiction and the pragmatic reality is instructive. It is easier to get a contract for a book because the calendar says it’s propitious than because the idea is intrinsically good. There is an argument that says marking anniversaries is “good for” the artists concerned because it gets “neglected” figures noticed. But wasn’t Warlock’s music as vividly viable 10 or 15 years ago, as Stevenson’s fiction proved to be? In the same way, what’s more interesting than how much coverage the composer Paul Hindemith receives next year - yes, his centenary - is why he’s been so sorely neglected over the last twenty five. Will media flattery again prove deceptive?

The heavy element of superstition sometimes prompts wild conclusions. In 1984, a year already hollow with resonance, music critics found themselves getting excited about the fact that it was exactly 50 years since the death of Delius, Elgar and Holst, and a half century since the births of Peter Maxwell Davies and Harrison Birtwistle. Ergo, “a watershed in British music”. More objective and reasoned evidence suggests that the timing’s out by at least 10 years in either direction.

Increasingly over the last 25 years (or maybe it’s 26) there’s been a growing tendency to see history in all its branches dividing itself into neat, decade-length parcels. The Nineties (1890s, that is) were probably the first to be so designated, and there’s been a steady supply of adjectives - Naughty, Hungry, Swinging - and other descriptives, like “the Me Decade”, ever since. Just as we never used to go into the movies at the official start, simply when we got there, so we can’t chop the more complex narrative of history up into separate reels and features. There’s a clear logic to an idea like that of “the long 19th century”, which doesn’t end at Hogmanay 1900, but in August 1914. Look at the 50s. If you see them beginning in 1950 and ending in 1959, then it’s possible to argue that they were narrowly conformist and unenterprising. If you shift the focal length slightly and see them starting with the surrender of Japan and continuing until the Kennedy assassination, which is an equally consistent historical span, then they take on a new character, which eight extra years doesn’t completely explain. There’s substantial critical literature now to be able to assert that almost every artistic innovation of the supposedly forward looking and experimental 60s was actually a product of the previous decade (old-style) and that the 60s were, by contrast, both conservative and, following Dallas, paranoically suspicious.

Next year will undoubtedly see considerable discussion of one event that has managed to remain in full view for much of the intervening period, the bombing of Hiroshima and then the considerably less justified sequel at Nagasaki. Fifty years have passed, and without the often-threatened repetition, or the nightmare scenario that a whole generation grew up with. Has that nightmare been prevented or purged very largely by the fact that the lessons of Hiroshima have been kept firmly in view? No one in the Maastricht-haunted year that is passing seems to have mentioned or recalled that in 1194 Richard I renounced his claim to the throne of England, and ceded authority to the Holy Roman Emperor. There’s no more relevance to the detail than there would have been if it had happened in 1273 or 1635, but you’d think that in the circumstances someone might have noticed the coincidence. Because just as we do seem to have an inbuilt need for rhyme and for certain apparently fortuitous kinds of harmony, so is there a profound psychological need for rhymes and harmonies in history. Editors, as usual, are aware of such needs and act on them. Digging into the sequence at seeming random can seem uncomfortably dissonant.

The only respectable solution is a version of what Matthew Arnold (a man one rarely feels the need to quote until the age of 40) recommended: to see life steadily and to see it whole. Since that is a quixotic ambition, there is nothing inherently wrong with looking at an artist’s work again or at the implications of a historical event simply because a round number of years has passed. The danger lies in only tasting arbitrarily designated vintages. There was once a man who bid for and won an exceptionally rare bottle of burgundy. He took pains to tell everyone that he didn’t want it just to keep in his cellar, but to drink, but he decided to hang on to it for another five years, just to round up the arithmetic. What had once (eh, but when?) been a richly contoured vintage was by the time he corked it a fluid closely resembling the stuff Sarson’s make for chips.

Mutatis mutandis.