Phineas Parkhurst Quimby
Spirits: Are They Substance or Shadow?May 1862
Is a spirit a reality, i.e., a truth - or is it the work of superstition? I affirm that it is the work of superstition. There is just as much truth in a spirit as there is in the belief that spirits do exist. If a person believes a lie, to him it is a truth; not that the lie is a truth, but the belief is a truth to him, and he is affected by it, the same as though it was a scientific fact, capable of demonstration. The belief in the real existence of spirits is so universal that every person admits it, more or less.
Let us examine whence this spirit comes. The process of mind called “thinking” is a sort of sketch or draft for an idea or thing. For instance, a man wishes to construct a machine. He creates it in his mind, and this creation can be seen and described by a very sensitive person. Under the excitement of a superstitious fear of the dead, a man will create a being after his own idea. This also might be seen by another. I know this to be true, for upon this principle, I cure disease.
Ghosts and spirits, like diseases, are the invention of man's superstition, and the wisdom that can destroy one can destroy the other. Man, not knowing that the things he sees are ideas of his own or of someone else's creation, calls the thing seen a “spirit.” This gives rise to the idea of spirits of the dead, for the living have no disembodied spirit.
casts no shadow of himself, but when his wisdom is reduced to man's
understanding, that casts a shadow; therefore true wisdom is not
seen! Spirits are not produced from either of these causes. They come
from superstition. Destroy the superstition about death, and the
process of thinking of other things would stand. So long as people
think about the dead, so long there will be spirits; for thought is
spirit, and that is all the spirits there are.