Nether Stowey as it is today. Coleridge was staying at a farm nearby.
In a prefatory note to the first edition of his poem, Coleridge gives his account of the incident:- "In the summer of the year 1797, the author, then in ill health, had retired to a lonely farmhouse between Porlock and Lynton, on the Exmoor confines of Somerset and Devonshire. In consequence of a slight indisposition, an anodyne" (generally supposed to be two grains of opium) "had been prescribed, from the effects of which he fell asleep in his chair at the moment that he was reading the following sentence, or words of the same substance, in Purchas's Pilgrimage: 'Here the Khan Kubla commanded a palace to be built and a stately garden thereunto. And thus ten miles of fertile ground were enclosed with a wall.' The author continued for about three hours in a profound sleep, at least of the external sense, during which time he has the most vivid confidence that he could not have composed less than from two to three hundred lines; if that indeed can be called composition in which all the images rose up before him as things, with a parallel production of the correspondent expressions, without any sensation or consciousness of effort. On awakening he appeared to himself to have a distinct recollection of the whole, and taking his pen, ink, and paper, instantly and eagerly wrote down the lines that are here preserved. At this moment he was unfortunately called out by a person on business from Porlock, and detained by him above an hour, and on his return to his room, found, to his no small surprise and mortification, that though he still retained some vague and dim recollection of the general purport of the vision, yet, with the exception of some eight or ten scattered lines and images, all the rest had passed away like the images on the surface of a stream into which a stone has been cast, but, alas! without the after restoration of the latter!"
Many scholars and others cannot accept this account. Robert Prinsk the American poet believes the story to be an invention. Coleridge, he suggests, 'like most writers', needed periods of procrastination and, like his fellow authors, was at pains to keep the fact a secret and not above constructing an untruth to cover it. Others think that Coleridge found his poem to be basically unsatisfactory and needed to excuse it in some way. On his own admission it is fragmentary and unfinished - possibly, some maintain, because he considered it flawed and wanted out. What better way than to have been interrupted whilst in the white heat of composition - for want of a better word?
I have some difficulty with these versions of events. On the one hand we have Coleridge waking from an (apparently) opium-induced dream with a complete poem remembered with such accuracy that no effort of composition was called for. We must suppose that, given no interruption, he would successfully have committed the whole two- to three-hundred lines to paper. The ability to recall a dream of that length in its entirety is, to say the least, exceptional. But to get it down on paper would have been more so. Had I got up in the early hours of the morning to jot down the details of my lengthy dream involving the fancy dress ball, I know what would have happened: the act of writing, as I recorded the early parts of the dream, would have caused the later parts to fade. It is only now, after I have carried the details around in my head for a while, that I would be able to transcribe it all - I think! But who am I to compare Coleridge's Rolls Royce of a memory with my old banger? Fair enough, but what I am saying is that the story does not work for me the way that dreams and memories normally work. And there is a further and more knotty problem: the intruder himself. Coleridge is generous with detail in his account, in everything except the matter of the key figure, the visitor, a person shrouded in mystery. I say 'himself', but the fact remains that we do not even know for sure that we are speaking of a man. The male gender has generally been assumed, but it could as easily have been a woman, or even a child. We do not know who or what this individual was to Coleridge or what was the business that detained them for so long. We know nothing about the intruder except that s/he was "a person from Porlock" - and why is that fact so important? The figure is blurred and does not seem to belong with the clarity of Coleridge's description of events leading up to its appearance. On the other hand, I can find no evidence to support the idea that Coleridge lied, and therefore, I do not think we should suggest that he did.
Where does that leave us? There does seem to me to be another possible scenario. It goes something like this :- With or without the agency of his "two grains of opium", Coleridge has some sort of day-dream or reverie, or he wakes from sleep with the dream (again, probably opium-induced though not necessarily so) still running in his mind, and as the vision unfolds he sits down to record the lines which appear like sub-titles to a film - or maybe they were spoken by a voice-over, for Coleridge's description would allow of either interpretation. Fifty lines or thereabouts into the manuscript there is a sound from outside; a horse and rider passing by, a drunken reveller making his merry way home (unlikely: the farmhouse is remote, remember) or there is a knock at the door, which Coleridge ignores. It is even possible that the vision was waning a bit at this point and that to refresh it Coleridge took another grain of opium. None of these conjectures are essential to the tale, though all are possible enough to make this version more likely. For whatever reason, which may or may not have been an extraneous one, this is the point at which the figure from Porlock makes its appearance, not in the flesh, but as a figment of the reverie, and we may suppose that it is this intrusion that pushes the vision off in a quite different direction, one that Coleridge cannot fit into the poem. It takes an hour or more to get rid of the intruder, i.e. for the reverie to run its course and for Coleridge to be free of it. At which point he again sits himself down and tries to recall the original vision, which he cannot, for it has been overlaid by the fresher, stronger one involving the mystery figure. Why "from Porlock"? We would have to know what significance Porlock held for Coleridge at this particular moment of time. And why no more information concerning the intruder? Because Coleridge knows no more; the dream tells the dreamer only what is relevant to its purposes.
Kubla Khan as it has come down to us is only 54 lines long. Because it was never completed, the phrases "Person from Porlock", "Man from Porlock", or just plain "Porlock", have become literary allusions to, or metaphors for, unwanted intruders or for anything that hinders or prevents an author from writing - including procrastination.