The Spirits' Book
Book Two - The Spirit World
Chapter VIII - Emancipation of the Soul
435. Can somnambulists see other spirits?
“That depends on the nature and level of their abilities. Most of them see other spirits perfectly well, but they do not always recognize them as spirits and mistake them for physical beings. Somnambulists and especially those who know nothing about Spiritism often make this mistake. They do not understand anything pertaining to spirits and are shocked to see them in human form. This leads them to believe that they are living persons.”
The same effect is felt at death in those who believe that they are still alive. Nothing about them appears to have changed. The spirits around them seem to have bodies like ours, and they mistake the appearance of their own body with that of a real body.