ANYONE who thinks things through carefully can see that it is not the body that thinks, because the body is material. Rather, it is the soul, because the soul is spiritual. The human soul, whose immortality has been the topic of many authors, is our spirit; it is in fact immortal in all respects, and it is also what does the thinking in our bodies. This is because it is spiritual and the spiritual is open to the spiritual and lives spiritually, through thought and intention. So all the rational life we can observe in our bodies belongs to the soul and none of it to the body. Actually, the body is material, as just noted, and the matter that is proper to the body is an addendum and almost an attachment to the spirit.
Its purpose is to enable our spirit to lead its life and perform its services in a natural world that is material in all respects and essentially lifeless. Since matter is not alive—only spirit—we may conclude that whatever is alive in us is our spirit and that the body only serves it exactly the way a tool serves a live and activating force. We may of course say that a tool works or moves or strikes, but it is a mistake to believe that this is a property of the tool and not of the person who is wielding it.
Since everything that is alive in the body—everything that acts and feels because of life—belongs to the spirit alone and none of it belongs to the body, it follows that the spirit is the actual person. In other words, we are essentially spirits and have much the same form as well. You see, everything that is alive and sensitive within us belongs to our spirit, and there is nothing in us, from head to toe, that is not alive and sensitive. This is why when our bodies are separated from our spirits, which is called dying, we still continue to be human and to be alive.
I have heard from heaven that some people who die, while they are lying on the slab, before they have been revived, are still thinking in their cold bodies, and cannot help but feel that they are alive, but with the difference that they cannot move a single part of the matter that makes up their bodies.
We could not think or intend if there were no agent, no substance as the source and focal point of thought and intent. Anything we may imagine happening apart from a substantial agent is nothing. We can tell this from the fact that we could not see without an organ serving as the agent of our sight or hear without an organ as the agent of our hearing. Apart from these, sight and hearing would be nothing, would not exist. The same holds true for thought, which is inner sight, and for attention, which is inner hearing. Unless these happened in and from agents that are organic forms, as subjects, they would not happen at all.
We may gather from this that our spirit is also in a form and that it is in human form, that it enjoys sensory organs and senses when it is separated from the body just as it did when it was in it. We may gather that all of the eye’s life, all of the ear’s life, in fact all of our sensory life belongs not to the body but to the spirit that is in these functions and even in their least details. This is why spirits see and hear and feel just as much as we do, though after we have left the body this does not happen in the natural world but in the spiritual one. The reason the spirit was sensitive on the natural level when it was in the body is that it worked through the material part that was appended to it. However, it was still spiritually sensitive in its thinking and intending.
from Heaven and Hell, Sections 432-434