Man is an essentially superstitious and fearful animal. Take away the herd's Christian gods and saints and they will without failing come to worship...something else.
Any magazine-cover hack can splash paint around wildly and call it a nightmare, or a witches sabbath or a portrait of the devil; but only a great painter can make such a thing really scare or ring true. That's because only a real artist knows the anatomy of the terrible, or the physiology of fear.
Science, already oppressive with its shocking revelations, will perhaps be the ultimate exterminator of our human species - if separate species we be - for its reserve of unguessed horrors could never be borne by mortal brains if loossed upon the world.
The unknown ... became for our primitive forefathers a terrible and omnipotent source of boons and calamities visited upon mankind for cryptic and wholly extra-terrestrial reasons, and thus clearly belonging to spheres of existence whereof we know nothing and wherein we have no part.
It is in dreams that I have known the real clutch of stark, hideous, maddening, paralysing fear. My infant nightmares were classics, & in them there is not an abyss of agonising cosmic horror that I have not explored. I don't have such dreams now - but the memory of them will never leave me. It is undoubtedly from them that the darkest & most gruesome side of my fictional imagination is derived.
More wonderful than the lore of old men and the lore of books is the secret lore of the ocean. Blue, green, grey, white, or black; smooth, ruffled, or mountainous; that ocean is not silent. All my days I have watched it and listened to it, and I know it well. At first it told to me only the plain little tales of calm beaches and near ports, but with the years it grew more friendly and spoke of other things; of things more strange and more distant in space and time.
Thus I began my systematic though half-bewildered tour of Innsmouth's narrow, shadow-blighted ways. Crossing the bridge and turning toward the roar of the lower falls, I passed close to the Marsh refinery, which seemed to be oddly free from the noise of industry. The building stood on the steep river bluff near a bridge and an open confluence of streets which I took to be the earliest civic center, displaced after the Revolution by the present Town Square.
Though not a participant in the Business of life; I am, like the character of Addison and Steele, an impartial (or more or less impartial) Spectator, who finds not a little recreation in watching the antics of those strange and puny puppets called men.
All life is only a set of pictures in the brain, among which there is no difference betwixt those born of real things and those born of inward dreamings, and no cause to value the one above the other.
Rome was so mighty that it could not fall. It had to vanish in a cloud, like so many of the mythical heros of antiquity, and to receive its apotheosis among the stars before men became fully aware that it had vanished from the earth!