The Shadow out of Time by H.P. Lovecraft

After twenty-two years of nightmare and terror, saved only by a desperate conviction of the mythical source of certain impressions, I am unwilling to vouch for the truth of that which I think I found in Western Australia on the night of July 17–18, 1935. There is reason to hope that my experience was wholly or partly an hallucination-for which, indeed, abundant causes existed. And yet, its realism was so hideous that I sometimes find hope impossible. If the thing did happen, then man must be prepared to accept notions of the cosmos, and of his own place in the seething vortex of time, whose merest mention is paralysing. He must, too, be placed on guard against a specific lurking peril which, though it will never engulf the whole race, may impose monstrous and unguessable horrors upon certain venturesome members of it. It is for this latter reason that I urge, with all the force of my being, a final abandonment of all attempts at unearthing those fragments of unknown, primordial masonry which my expedition set out to investigate.

Assuming that I was sane and awake, my experience on that night was such as has befallen no man before. It was, moreover, a frightful confirmation of all I had sought to dismiss as myth and dream. Mercifully there is no proof, for in my fright I lost the awesome object which would-if real and brought out of that noxious abyss-have formed irrefutable evidence. When I came upon the horror I was alone-and I have up to now told no one about it. I could not stop the others from digging in its direction, but chance and the shifting sand have so far saved them from finding it. Now I must formulate some definitive statement-not only for the sake of my own mental balance, but to warn such others as may read it seriously.