The following is from "Fanatical Guides," an article in The American Quarterly Review of September 1830, volume 8 (pp. 227 to 245). It describes, in Thompson's own words, his experience with spiritism:
"My honesty in expressing my sentiments, nearly destroyed my fellowship with the whole body of professing Christians, and caused me much bitterness. I appeared almost as an isolated individual, feeling no interest in any party, nor almost in any terrene object. The subject of religion seemed to me to wear a gloomy picture. For a time, I desisted from every religious meeting whatever, and for several months dreaded insanity. My application to study was inexpressibly intense : I never slept more than two or three hours. The deity of Jesus, the immortality of the soul, and some other subjects, continually kept my mind in excitement. Having adopted Materialism on the Priestleyan plan, I could not admit the existence of spirits in our world; for all antiquity supposed spirits to have been originally men : but if there had been no resurrection, there could be no human spirits.
"I will now proceed to relate things, just as I have before done, agreeably to the views and impressions I then had ; leaving every one to form his own opinion. I acknowledge, my mind was in a state of great excitement, at the time I had these extraordinary impressions; but it did not then seem to me, nor does it yet, that the degree of the excitement was adequate to the phenomena. I awoke, one night, and heard a considerable noise in my room. I listened carefully for some time, and the sound was that of a thousand pens, writing in great haste what was dictated. I heard a voice very distinctly, saying, - ‘In all your writings, be careful to represent Jesus as only the instrument of God in all he does.’ I immediately interrupted, by exclaiming,- ‘Silence! I’ll not believe one of you.’ The noise immediately stopped; and I was often afterward sorry that I had interrupted the dictation. I examined; but there was no person in the room, the door being locked, and none had yet arisen in the house.
"Not long after, sleeping in the same room, I awoke by pressure, which removed immediately on awaking. I began to reflect, whether it was a dream, or an external force applied to my body. Whilst I doubted, some being took hold of my hands, and pressed with violence, which excited in me great surprise. My hands were let loose, but, in one minute, they were again seized, with renewed violence. I then cried, - 'Let me loose! I believe! do not injure me! I am entirely satisfied of your existence!’ The pressure on my hands was immediately removed, and I then felt greatly agitated, and tossed in my bed. In two minutes after, my hands were seized a third time : I then complained loudly, but, in a minute of time, I was again set at liberty. I leaped on the floor, determined that I would make full proof, whether any person had got into the room : though I believed that no man could apply so much strength as I had experienced on my hands. The first thing I did was to examine the door, which I found as I had left it, locked, with they key in the inner side. I took the key out of the door and again trying it, found it fast. I then groped all over the room, but found nobody. I retired to my bed, placing the key under me, and waiting for the light of day.’"