Psyches

Psyche is basically a fancy word for "the mind."

If a mage or mystic magically separates his mind from his body to fly around, he is essentially uncoupling his psyche from his body. If a spell caster tries to read someone’s mind, dazzle them with a magical charm, alter memories or do some other magical mind effect, that person is attacking the other beings Psyche.
Psyches are both more vulnerable and more powerful when the owner of a Psyche is asleep. Some mystics can accomplish amazing feats of power while asleep. Other mystics can really mess someone up by attacking their mind while they sleep.
In game terms, all creatures with a Willpower score have a Psyche. In metaphysical terms, any creature that feels things beyond hunger, pain, and basic fight or flight instinct has a Psyche.
A person who loses his Psyche (or sends his Pysche on a temporary trip into the Astral Plane) is a vegetable. Barring people who can astral project, totally separating a person from his or her Pysche is extremely hard to do. It is slightly easier to pull of this effect on someone who is asleep and dreaming. A mortal who is separated from their psyche will probably die within a few days, maybe a week if they have a doctor or healer tending them. Such a person could survive two or three weeks if they are being cared for by someone with magical healing abilities.
Much easier to do than a total separation, but still difficult, a Psyche can be wounded or put to sleep. A person with a damaged or impaired psyche can still move and act but is likely listless, monotone and emotionless. This can happen if the same person is subjected to magical or psionic mind control over and over again.
A ghost is essentially a hybrid of Mortis and Psyche and little else. A Psyche can live by itself without even a Mortis, but this is fairly rare, essentially a Psyche like literally a creature of pure thought. A disembodied Psyche makes its way into the Astral Plane and adapts to existence there, or it fades away into nothingness.
Rarest of all is the artificial Psyche. If you encounter a talking sword or magic mirror or something like that, it probably has an artificial Psyche (or someone’s soul was imprisoned in it). Artificial Psyches are very hard to create, a feat only a few exceptionally powerful magic users can pull off.

Type

Metaphysical, Astral