From my experience, when a human being dies and his or her spirit lingers, that spirit retains its personality, memories, and ability to reason. Depending on how you accept that ghosts (human remnants specifically) become earthbound, this retention of a large portion of who and what they were in life is a fundamental characteristic of lingering human spirits. There are phenomenon labeled as ghosts which are not human spirits. These can manifest as an apparition of a person, as a sense of their presence, the sound of their voice, even the scent of their perfume. In some rare cases, these manifestations will involve all of these things. The manifestations are not necessarily static. Quite typically, they repeat a specific series of actions, over and over again. The vast majority of manifestations witnessed on the field of Gettysburg fall into this category.
These manifestations are what I’ve called “memory ghosts.” They are an imprint or an echo that has been stamped upon the energy of the subtle reality. They are almost always the product of a highly emotional situation or event: a murder, a battle, a suicide. They have all the sentience and free will of an image projected onto a screen. They repeat the seem actions endlessly because they are nothing more than a recording on infinite repeat. As the energy that made the impression fades over time, the repetitions can fade or cease altogether. But the spirit of the actual person who generated the energy to create this effect is long, long gone.
Some constructs exist that might be perceived as ghosts. The most famous example of this is one given by John Keel in The Mothman Prophecies (now a completely inaccurate motion picture!). There is a house in Greenwich Village where residents kept seeing a figure in dark clothes, a flowing cape, and a wide-brimmed slouch hat stalking through the corridors. The face of the figure was always indistinct, but some said it had a very piercing, intense gaze. This apparition was seen numerous times by a succession of people. Concluding that the house was haunted, the history of the house was researched, but it seemed that no one had ever died in the residence (I could go on my rant about how everyone seems to think that someone has to have died in a house in order for their spirit to haunt it — suffice it to say that it just ain’t so). Someone came up with the theory that this figure was the ghost of a Civil War soldier or even a spy — it projected a sneaking, almost sinister air about it to those who perceived it.
After coming up with dead-ends on the identity of this mysterious figure, someone learned that the house had once been the residence of a rather prolific writer by the name of Walter Gibson. Gibson had spent some of his most productive years in the house, turning out page after page in a series which revolved around one specific character. The character was The Shadow — “Who knows what evil lurks in the hearts of men? The Shadow knows … “ as the old radio show used to go.
It just so happens that the Shadow stalked around in dark clothes with a muffled face, a flowing cape, and a wide-brimmed slouch hat. The “ghost” in the Greenwich Village house was a construct birthed by Gibson’s fertile imagination and all the energy he put into the form as he worked on his series of tales.
So this brings us back to real, legitimate ghosts. Once again, I define “ghost” as the spiritual remains of a human being who has died and lingered here as opposed to moving on to whatever version of the Afterlife exists beyond this place (The Tibetan Book of the Dead offers some good insights into this, and I’d have to say my own views on the whole process are largely in keeping with that of the Tibetans). These spirits are just like people — except they no longer wear flesh. As such, they can lie just like people do; they can have agendas just like people do; and they can be varying shades of beneficial and malevolent just like people are.
It’s a common belief, propagated mainly through Medieval necromantic traditions, that ghosts, once they’ve crossed over, become omniscient. This is the root of necromancy being a diviniatory technique. It was beleived that the dead were privy to all manner of knowledge and secrets that were obscured from the living by the veil separating the living from the dead. But this belief in the omniscience of spirits is just another misconception that’s grown out of the mystique living people tend to apply to the dead. In my experience, while their perceptions from that side of things are different, they are not omniscient by any means. They do tend to be more empathic/telepathic than your average incarnated human, but this is mainly because they exist on the level of pure energy and all communication and/or interaction occurs on this level.
Energy does sustain them. However, they are perfectly capable of taking it for themselves. When you are alive, you are both spirit and matter — and just as your physical body sustains itself with food and water and air, your subtle body sustains itself with the energy from the world around you. Some of this energy is in the food you eat; some of it is exchanged with the environment through the process of breathing (hence the layered meaning of breath/life/spirit with such words as prana, chi, and even the Swahili roho); and some is gained through more subtle means (we can get into the ramifications this has on the reality of vampirism in another thread). For the most part, a living being’s interaction with and intake of energy occurs on the same unconscious and instinctual level as breathing — you don’t need to know the mechanics of it or even what muscles you’re flexing in order to do it — it’s hard-wired into the organism. Survival’s great that way.
The ability to take in sustaining energy (and expel energetic byproduct) is similarly a natural process for the spirits of the dead. However, there is usually a slightly more active element involved. Consider energy the food of the dead. You don’t eat a hamburger just by thinking about it. So it is with the spirits — they do have to actively forage for their “food” although it’s not necessary for them to consciously understand the whole process by which they eat and digest it (consider how many embodied beings would be in trouble if we had to understand the mechanics of physical digestion just to gain any benefit from our regular meals).
Spirits certainly appreciate gifts of energy — and this is one way I have of thanking them for a service rendered. Think of all the funerary systems the world over that leave food offerings to the dead while acnowledging that the food itself serves as a symbol for the subtle nourishment that the spirits derive from such sacrifice. However, if you’re working with spirits, don’t let them feed off of you without restraint. There’s no reason for this. Set guidelines and groundrules for what is acceptable and unacceptable behavior. Make sure the spirits know that these don’t apply only to you, or else you may have visitors to your home complaining of being tired all the time. Be very clear that the spirits you work with are to take energy that is offered willingly only — and if they start breaking this cardinal rule, make certain there are consequences.
As for what use a human spirit can be put to? You can sit around and talk to it — I find some of them vastly entertaining. They can be put to work as house guardians. This runs much along the same lines as creating a construct to do that job — except most constructs have a limited intellect and frequently can only do what they’ve been programmed to do. A human spirit is just like having another person in the house, but someone who can watch it from the otherside. They can think, reason, make judgement calls on what to do, etc.,
Summoning any other sort of entity for this work yields about the same results — it’s just that some entities don’t operate on remotely human principles, and so their behavior & reactions are harder to predict. I suppose I like the predictability of human spirits — with a good grasp of human psychology, it’s pretty easy to know what they want, how to make them happy, and how to get them to do a job for you. The other benefit is you’re working with something that you can meet on equal terms. Unlike a lot of others who work with spirits, I prefer not to bind or compel otherworldly entities. Constructs, as created things, are a little too much like servants or slaves to me, and bound entities are worse. So I prefer working with spirits that I can relate to as friends, companions, and equals, which means the vast majority of the disembodied I work with wore human flesh at some point in their existence.