The mystery began, without forewarning or prescience, on a quiet evening in July, after the scimitar-shaped moon had sheathed itself in the firs and hemlocks. I was sitting in my cabin, reading for relaxation a detective story whose title I have since forgotten. The day had been quite warm; there was no wind in that sequestered valley; and the oil lamp was burning steadily between the half-open door and the wide windows.

Then, on the still air, there came a sudden aromatic perfume that filled the cabin like a flooding wave. It was not the resinous odor of the conifers, but a rich and ever-deepening spice that was wholly exotic to the region—perhaps alien to the Earth. It made me think of myrrh and sandal and incense; and yet it was none of these, but a stranger thing, whose very richness was pure and supernal as the odors that were said to attend the apparition of the Holy Grail.

Even as I inhaled it, startled, and wondering if I were the victim of some hallucination, I heard a faint music that was somehow allied to the perfume and inseparable from it. The sound, like a breathing of fairy flutes, ethereally sweet, thrilling, eldritch, was all about me in the room; and I seemed to hear it in my inmost brain, as one hears the sea-whisper in a shell.

I ran to the door, I flung it wide open, and stepped out into the azure-green evening. The perfume was everywhere, it arose before me, like the frankincense of veiled altars, from the tarn and the hemlocks, and it seemed to fall from the stilly burning stars above the Gothic trees and granite walls, to the north. Then, turning eastward, I saw the mysterious light that palpitated and revolved in a fan of broad beams upon the hill.

The light was soft, rather than brilliant, and I knew that it could be neither aurora nor aeroplane beacon. It was hueless—and yet somehow it seemed to include the intimation of a hundred colors lying beyond the familiar spectrum. The rays were like the spokes of a half-hidden wheel that turned slowly and more slowly, but did not change its position. Their center, or hub, was behind the hill. Presently they became stationary, except for a slight trembling. Against them, I saw the bowed masses of several mighty junipers.

I must have stood there for a long while, gaping and staring like any yokel who beholds a marvel beyond his comprehension. I still breathed the unearthly odor, but the music had grown fainter with the slackening of the wheel of light, and had fallen to a sub-auditory sighing—the suspicion of a murmur far away in some undiscovered world. Implicitly, though perhaps illogically, I connected the sound and the scent with that unexplained luminance. Whether the wheel was just beyond the junipers, on the craggy hill-top, or a billion miles away in astronomic space, I could not decide; and it did not even occur to me that I could climb the hill and ascertain this particular for myself.

My main emotion was a sort of half-mystic wonder, a dreamy curiosity that did not prompt me to action. Idly I waited, with no clear awareness of the passing of time, till the wheel of rays began once more to revolve slowly. It swiftened, and presently I could no longer distinguish the separate beams. All I could see was a whirling disk, like a moon that spun dizzily but maintained the same position relative to the rocks and junipers. Then, without apparent recession, it grew dim and faded on the sapphire darkness. I heard no longer the remote and flute-like murmur; and the perfume ebbed from the valley like an out-going tide, leaving but elusive wraiths of its unknown spicery.

My sense of wonder sharpened with the passing of these phenomena; but I could form no conclusion as to their origin. My knowledge of natural science, which was far from extensive, seemed to afford no plausible clue. I felt, with a wild thrilling, half-fearful, half-exultant, that the thing I had witnessed was not to be found in the catalogues compiled by human observers.

The visitation, whatever it was, had left me in a state of profound nervous excitement. Sleep, when it came, was intermittent; and the problematic light, perfume, and melody recurred again and again with my dreams with a singular vividness, as if they had stamped themselves upon my brain with more than the force of normal sensory impressions.

I awoke at earliest dawn, filled with a well-nigh feverish conviction that I must visit the eastern hill immediately and learn if any tangible sign had been left by the agency of the turning beams. After a hasty and half-eaten breakfast, I made the ascent, armed with my drawing-pad and pencils. It was a short climb among overbeetling boulders, sturdy tamaracks, and dwarf oaks that took the form of low-growing bushes.

The hill-top itself comprised an area of several hundred yards, roughly elliptic. It fell gently away toward the east, and ended on two sides in sheerly riven cliffs and jagged scarps. There were patches of soil amid the enormous granite folds and out-croppings; but these patches were bare, except for a few alpine flowers and grasses; and the place was given mainly to a number of gnarled and massive junipers, which had rooted themselves by preference in the solid rock. From the beginning, it had been one of my favorite haunts. I had made many sketches of the mightily mortised junipers, some of which, I verily believe, were more ancient than the famed sequoias, or the cedars of Lebanon.

Surveying the scene with eager eyes in the cloudless morning light, I saw nothing untoward at first. As usual, there were deer-tracks in the basins of friable soil; but apart from these, and my own former footprints, there was no token of any visitor. Somewhat disappointed, I began to think that the luminous, turning wheel had been far-off in space, beyond the hill.

Then, wandering on toward the lower levels of the crest, I found, in a sheltered spot, the thing that had previously been hidden from my view by the trees and out-croppings.

It was a cairn of granite fragments—but a cairn such as I had never beheld in all my mountain explorations. Built in the unmistakable form of a star with five blunt angles, it rose waist-high from the middle of a plot of intersifting loam and sand. About it grew a few plants of mountain phlox. On one side were the charred remnants of a tree that had been destroyed by lightning in recent years. On two other sides, forming a right angle, were high walls to which several junipers clung like coiling dragons with tenacious claws, embedded in the riven rock.

On the summit of the strange pile, in the center, I perceived a pale and coldly shining stone with star-like points that duplicated and followed the five angles. This stone, I thought, had been shaped by artificial means. I did not recognize its material; and I felt sure that it was nothing native to the region.

I felt the elation of a discoverer, deeming that I had stumbled on the proof of some alien mystery. The cairn, whatever its purpose, whoever its builders, had been reared during the night; for I had visited this very spot on the previous afternoon, a little before sunset, and would have seen the structure if it had been there at that time.

Somehow, I dismissed immediately and forever all idea of human agency. There occurred to me the bizarre thought that voyagers from some foreign world had paused on the hill and had left that enigmatic pile as a sign of their visit. In this manner, the queer nocturnal manifestations were accounted for, even if not fully explained.

Arrested by the weird enigma of it all, I had paused on the verge of the loamy basin, at a distance of perhaps twelve feet from the cairn itself. Now, my brain on fire with fantastical surmise, I stepped forward to examine the cairn more closely. To my utter dumbfoundment, it appeared to recede before me, preserving the same interval, as I went toward it. Pace after pace I took, but the ground flowed forward beneath me like a treadmill; my moving feet descended in their former tracks; and I was unable to make the least progress toward the goal that was apparently so near at hand! My movements were in no sense impeded, but I felt a growing giddiness, that soon verged upon nausea.