Read it through once

I have said that the sole effect of my somewhat childish experiment--that of looking down within the tarn--had been to deepen the first singular impression. There can be no doubt that the consciousness of the rapid increase of my superstition--for why should I not so term it?--served mainly to accelerate the increase itself. Such, I have long known, is the paradoxical law of all sentiments having terror as a basis. And it might have been for this reason only, that, when I again uplifted my eyes to the house itself, from its image in the pool, there grew in my mind a strange fancy--a fancy so ridiculous, indeed, that I but mention it to show the vivid force of the sensations which oppressed me. I had so worked upon my imagination as really to believe that about the whole mansion and domain there hung an atmosphere peculiar to themselves and their immediate vicinity--an atmosphere which had no affinity with the air of heaven, but which had reeked up from the decayed trees, and the grey wall, and the silent tarn--a pestilent and mystic vapour, dull, sluggish, faintly discernible, and leaden-hued.