Ghost, Spirit
The ghost is a "primitive" form of spirit, an autonomous activity in the unconscious that, perhaps due to its embodiment, can communicate with the ego—"embodied autonomous complexes." Ghosts and spirits belong to "the other side" and are therefore perceived as uncanny. In dreams, the ghost can represent a blocked part of ourselves that seeks to incarnate in the body, to become part of life.
Spirit
The spirit is associated with the wind, whether it is the rustling of treetops, a chilly draft, or ripples across the sea. The spirit is “always an active, winged, swift being that enlivens, stimulates, urges, spurs, and inspires.” (Jung.) It is “the dynamic principle,” the antithesis of matter; that is, the opposite of the static and inert. The spirit is also, or perhaps consequently, associated with fire, both in religious texts (such as the burning bush) and in fairy tales.
The Wise Old Man
In dreams, the archetypal image of “the wise old man” symbolizes the spiritual principle; more rarely, dwarf-like figures or talking animals. (See Old Man.)
Revenant
There is also reason to consider whether ghosts in dreams—beings who "return"—represent something from the past that is coming back. Ghosts suggest something ancient in dreams.
Procession of Ghosts
It is not uncommon for a procession of ghosts or a gathering of "the dead" or ancestors to appear in our dreams at critical moments, when we face important decisions or have taken decisive steps in our lives, which draw the attention of "the others."
Ghosts as Ancestors
Ghosts are what remains of earlier lives, "what are called the spirits of the ancestors." (Visions, p. 1266.) They are, so to speak, innate elements in our psychology and can constellate in our lives, appearing in our dreams as ghosts.
Poltergeist
Poltergeists and other hauntings belong to "the other side," that is, the unconscious. They may express the tangible presence of the unconscious. Since poltergeists tend to appear in the presence of prepubescent children, this phenomenon may suggest that the unconscious is intruding due to the dreamer's immaturity in the area the dream reflects.
Alchemy and Spirit
In alchemy, the concept and phenomenon of "spirit" recur frequently and are almost always associated with water; specifically, based on the original experience that heated water evaporates or becomes spiritualized. They imagined the spirit as being trapped in water, like the fish.