My wife has been teaching the Ancient Mariner to her A-Level set, and over dinner we found ourselves exploring Coleridge’s trickery with tenses.

The outline of the poem we remember is simple: a (present-tense) fable about an old man and a wedding guest book-ends the old man’s much longer (past-tense) story of fall and redemption. We know the poem begins “It is an ancient mariner”, shifts to flashback with “there was a ship”, then finally pulls us back to the present as the wedding guest “goes like one that hath been stunned”.

But the poem we remember isn’t the poem Coleridge wrote. Here are stanzas 3-5 of the 1828 version:

He holds him with his skinny hand,
‘There was a ship,’ quoth he,
‘Hold off! unhand me, greybeard loon!’
Eftsoons his hand dropt he.

He holds him with his glittering eye –
The Wedding-Guest stood still
And listens like a three years child:
The Mariner hath his will.

The Wedding-Guest sat on a stone:
He cannot chuse but hear;
And thus spake on that ancient man,
The bright-eyed Mariner.

We expect “holds” (x2), “quoth”, “listens” and “cannot chuse” to be in the present tense, and “there was a ship” to be in the past. But “dropt”, “stood”, “sat” and “spake” are all wrong. Not just wrong, but dizzyingly so: two consecutive stanzas shift tenses in mid-sentence (“stood still / And listens”; “cannot chuse… spake”).

It continues in similar fashion. Of 22 verbs in the framing narrative (the parts of the poem not spoken by the mariner, the wedding guest or any of the minor characters), 13 are in the present tense and 9 in the past. Likewise, the mariner’s past tense narrative repeatedly slips into the present at moments of stress or supernatural import.

What’s the effect of all this time-travel? Counterintuitively, that we don’t seem to notice it (at least not on a conscious level). Over the next few weeks I asked five or six poetry-loving friends – all attentive, literate close-readers who know the poem well – and none had spotted the tense-shifts. They all shared my incorrect memory of the poem as a simple flashback starting in the present tense then jumping back to the past.

It’s possible that I chose an unrepresentative sample. It’s also possible that the poem is too familiar: something we encounter early in life then take for granted without looking too closely at the mechanics. But I wonder if there’s something else going on, a kind of grammatical cognitive dissonance. Perhaps the reason we don’t notice the tense shifts is precisely because they’re so obtrusive and unsettling – part of what makes the poem mythic and dream-like. And that’s something we’d rather not see.

Unlike fairytales (which belong to the past), myths are simultaneously past and present. Dreams are less stable, regularly shifting person, tense, sequence and setting – but both myths and dreams share the ability to upset the grammatical conscious mind with its preference for rules and structure. This is what Coleridge’s blurred tenses mimic.

Over dessert this led us to the bigger question of time in the poem. As well as lurching between past and present like Doctor Who on a bender, the Mariner is repeatedly evasive on the subject of time. When is the poem set? Gustav Doré’s illustrations locate the wedding sometime in the middle ages, but apart from “minstrelsy” and some generic archaisms the poem itself doesn’t give us any clues. How long was the mariner’s voyage? How many years elapsed between his rescue by the hermit and waylaying of the wedding guest? How old was the mariner when he set out (presumably young enough to be a working crewmember)? And how ancient is the ancient mariner now?

If we wanted to get literal then the evidence suggests the voyage was relatively recent: the hermit still “lives in the wood” at the time the mariner tells his story, just as the pilot’s boy “now doth crazy go”. But this would be missing the point. The mariner exists outside historical time, passing from land to land and reliving his story in a continuous loop (to pass “like night” is, after all, to pass over and over again). It doesn’t matter if the voyage happened a week ago or several centuries ago: all that matters is that it happened. The mariner isn’t a character in a novel with a biographical backstory. He is an archetype, a symbol, a myth.

There are only three references to specific periods of time in the poem, two of them coming at crucial points immediately before and after the mariner’s ordeal. The albatross perches on the mast “for vespers nine” before the mariner shoots it, then an unspecified period of time later the dead men look on the mariner for “seven days, seven nights” before he blesses the water-snakes and lifts the curse. In between, quantifiable time is suspended. (The third reference is when the rescued mariner looks “like one that hath been seven days drowned”, although the insulating effect of the simile prevents this from disturbing the timelessness in quite the same way.)

Otherwise, the poem goes out of its way to be vague about lengths of time: “day after day, day after day”; “there passed a weary time…a weary time, a weary time”; “how long in that same fit I lay / I have not to declare”; “since then at an uncertain hour”. This is very different from the insistent – almost redundant – quantifying of physical things: “nine fathom deep” (x2); “whistled thrice”; “four times fifty living men”; “a thousand, thousand slimy things”.

By the time we’d had coffee and wandered home, a poem I’d loved for years had been subtly but beautifully changed. And at odd intervals since then I’ve found myself unable to resist the urge to tell people about it.