What are we going to make of "A Tale of the Ragged Mountains" like this? Among those who hear of it is Dr Templeton, a physician who has been treating Mr Bedloe for some time, and who has established a kind of 'magnetic rapport' with him. After Bedloe has finished, we learn that Dr Templeton, at the exact time of that strange experience, had written an account from his own memory of those riots in Benares of the year 1870 in which his good friend, the young officer Oldeb, had died in an ill-judged attack. More coincidences: there is a portrait of Oldeb that remarkably resembles Bedloe, whose name incidentally is almost what you get when you read the officer's name backwards.
1) Two possible ways of explanation suggest themselves: one based on metempsychosis, the other based on hypnosis. Let's begin with the latter. The explanation would go somewhat like this: Dr Templeton is an enthusiastic follower of the theories and practices of Mesmerism, which postulates an 'animalistic magnetism' that accounts for a deep connection between physician and patient. Treating Bedloe, Templeton has achieved a remarkably stong influence on him: "between Doctor Templeton and Bedloe there had grown up, little by little, a very distinct and strongly marked rapport, or magnetic relation. I am not prepared to assert, however, that this rapport extended beyond the limits of the simple sleep-producing power; but this power itself had attained great intensity. [...] the will of the patient succumbed rapidly to that of the physician, so that [...] sleep was brought about almost instantaneously, by the mere volition of the operator, even when the invalid [i.e. Bedloe] was unaware of his presence." (941)
Given this way of influence without observable interaction, perhaps Templeton's recounting and writing down of his earlier experiences have been sufficient to draw Bedloe, in the solitude of his walk (and under the influence of a strong dose of morphine; 942, 943) into a vision that shared its content with Templeton's memories. Templeton, as it were, telepathically transferred the recall of what he eyewitnessed a long time ago into Bedloe's weakened and suggestible mind, by either deliberate or accidental use of his 'magnetic' connection with his patient.
So that would be one possible explanation of what happened to Bedloe; the one based on hypnosis. If it rather seems bizarre to you, then wait until we get to the other one, the one that's based on metempsychosis.
Before we get to that, however, let us check on the merits of the hypnosis explanation. On the one hand, it would account for the inexplicable similarity in content of Templeton's written tale and Bedloe's vision. On the other hand, it would be of no help with some of the other strange facts: no simple mental connection could have caused the resemblance in looks, and the close similarities in the names (spelled forward and backward), of Bedloe and Oldeb. So the 'magnetic rapport' between doctor and patient cannot be the whole story.
2) What about metempsychosis, then? The Greek term means soul-wandering, and the idea would be that in some sense, Bedloe is Oldeb, that the officer's soul was reincarnated in the other man. What Bedloe experiences on his trip is an actual memory from his previous life. We must remember that Bedloe, although a young man, has a certain air of coming from the past: "He certainly seemed young — and he made a point of speaking about his youth — yet there were moments when I should have had little trouble in imagining him a hundred years of age." (940)
Now this accounts for the coincidence in looks and names, and a couple of other details. But if that is what is going on, then how would we account for the apparent connection between Bedloe's experience on the trip and Templeton's writing an account of just those events? Perhaps we have taken it the wrong way round: we have assumed that Templeton is the sender and Bedloe the receiver. (Why does this seem the more natural reading?) But maybe we'll have to correct that. Maybe Bedloe's vision comes from an anamnesis of his soul, a remembrance of things past, and what he experiences is then sent via his 'magnetic' link to Dr Templeton. (Note also that Templeton is clearly shaken when listening to Bedloe's account. From this we can infer that he didn't suspect anything strange was going on when we was writing his account. Only once Bedloe has returned Templeton began to see the coincidences. So, strangely, Bedloe on his trip was aware that something extraordinary was going on; Templeton, writing his account, wasn't.)
Moreover, what Bedloe experiences is not a direct replay of Templeton's memories, for Bedloe experiences the whole thing from the point of view of Oldeb, not Templeton. This supports the interpretation that bases the vision onto metempsychosis, not thought transfer: if it were Templeton's memories that were transferred, then we would have expected the whole thing to play from Templeton's point of view.
But then why is the story set up so that Templeton doesn't merely receive the vision, but had himself been a witness of the original events fifty years ago? Why, for instance, couldn't Templeton just listen patiently to Bedloe's tale, then go off to a library and come up with the facts about India, Benares, the insurrection fifty years ago, and so on? What is the significance, for the story, that Templeton knew Oldeb himself?
3) Let's also note that much care is taken in the story to invoke the topos of independent verification, in a somewhat original manner: Templeton produces a notebook in which he has written an account of the very same events, at just the time when Bedloe, on his hike, had a vision of them.
The story doesn't state this, but we are obviously supposed to assume that what we would find in those pages would closely resemble what Bedloe had just narrated. (Templeton says so, but the actual text of the notes is not part of the story, nor does the narrator tell us anything else about them than what Templeton says.) So let's assume that Templeton's notes indeed contain a tale very like the one we've just heard from Bedloe. We are told by the narrator that the pages appear to have been freshly written.
4) So where does Bedloe's vision come from? Is it a case of soul-wandering, i.e. has the dead soldier's soul possessed the wanderer for a while, making him experience the events from around the time of his own (bodily) death? Or is it a case of thought transfer, i.e. has the connection between Templeton and Bedloe caused the latter to experience the events just as the former was writing them?
(Nothing precludes of course that Bedloe might have heard from Templeton about them. In fact, we could easily imagine the whole episode of Bedloe telling his story a pre-arranged confidence trick supposed to demonstrate super-natural powers. But even without assuming the intent to deceive, a simple explanation would be that Templeton may have talked about these events before and Bedloe just remembered the tale and visualized it under the influence of the lonesome setting out there in the mountains, the drugs, and possibly illness or exhaustion.)
The text supports both interpretations to some extent. That the 'magnetic' connection between Templeton and Bedloe has mitigated a transfer of Templeton's memories into Bedloe's vision seems mostly supported by the demonstration setup, that Bedloe is in fact a reincarnation of Oldeb, the officer and friend of Templeton's who died in Benares, seems to be supported by the similarity in appearance, and also by the subtle indication that Bedloe sometimes has an air of being a hundred years old.
Maybe the idea was to have it both at once. So then there would have been soul-wandering between Oldeb and Bedloe and a magnetic communication of Templeton's memories to the latter. However, if the guiding question is what accounts for the extraordinary thing that happens to the wanderer, then the answer seems to be overdetermined here. Bedloe, on this combined interpretation, lives through the experiences of his former incarnation and the recall of his physician which coincide with his trip; it's so vivid and coherent because it's his actual former live and the doctor's memories; and finally, it's triggered by his physical exhaustion and mental relaxation and via the magnetic rapport with Templeton. This seems to be too much of a good thing.
So here we are with two interpretations that are too weak individually and too strong if combined. That's a pity, because I'm now going to analyze an element in the story that seems to me particularly well done, namely: the way Bedloe's immersion in the world of his vision is narrated. I would have liked to have the question of the main story line out of the way; but as it is, it's going to hover unresolved over what I think can be extracted from that element.
 Edgar Allan Poe, "A Tale of the Ragged Mountains", in: The Collected Works of Edgar Allan Poe. Volume 3: Tales & Sketches II, edited by Thomas Ollive Mabbott, Cambridge: Belknap 1978, 935–953.
 The theory of Mesmerism with its 'magnetic rapport' that Poe builds into his story was widely discussed at his time. The view has been discarded long since, but there was some core of real phenomena behind it which is today known as hypnosis.
 But note that we're working here, of course, with the materials of the story. I don't mean to suggest that telepathy and the like take place in the real world. However, Poe himself might have assumed that at the time of writing his story — he might have taken it as valid science, that is, he might have been in the business of creating science fiction; or he might have assumed that his audience would take it as valid science. That's all that is required to base an interpretation of the story on it.
 It also seems to be a convention of the genre, at least for Poe, to kill off the host character after a successful soul transfer. That commonality might also count for categorizing it with metempsychosis plots. Compare "Morella", and "Ligeia".