“We are far from believing that all spirits that communicate at circles are of the classes called “Elemental”, and “Elementary”. Many – especially among those who control the medium subjectively to speak, write, and otherwise act in various ways – are human, disembodied spirits.
Whether the majority of such spirits are good or bad, largely depends on the private morality of the medium, much on the circle present, and a great deal on the intensity and object of their purpose.
If this object is merely to gratify curiosity and to pass the time, it is useless to expect anything serious. But, in any case, human spirits can never materialize themselves in propria persona. These can never appear to the investigator clothed with warm, solid flesh, sweating hands and faces, and grossly-material bodies.
The most they can do is to project their aethereal reflection on the atmospheric waves, and if the touch of their hands and clothing can become upon rare occasions objective to the senses of a living mortal, it will be felt as a passing breeze gently sweeping over the touched spot, not as a human hand or material body.
It is useless to plead that the “materialized spirits” that have exhibited themselves with beating hearts and loud voices (with or without a trumpet) are human spirits. The voices – if such sound can be termed a voice at all – of a spiritual apparition once heard can hardly be forgotten.
That of a pure spirit is like the tremulous murmur of an AEolian harp echoed from a distance; the voice of a suffering, hence impure, if not utterly bad spirit, may be assimilated to a human voice issuing from am empty barrel.”
H. P. Blavatsky