“As we have said before, the modern psychic force, and the ancient oracular fluids, whether terrestrial or sidereal, are identical in essence – simply a blind force. So is air. And while in dialogue the sound-waves produced by a conversation of the speakers affect the same body of air, that does not imply any doubt of the fact that there are two persons talking with each other.
Is it any more reasonable to say that when a common agent is employed by medium and “spirit” to intercommunicate, there must necessarily be but one intelligence displaying itself?
As the air is necessary for the mutual exchange of audible sounds, so are certain currents of astral light, or ether directed by an intelligence, necessary for the production of the phenomena called spiritual.
Place two interlocutors in the exhausted receiver of an air-pump, and, if they could live, their words would remain inarticulate thoughts, for there would be no air to vibrate, and hence no ripple of sound would reach their ears.
Place the strongest medium in such isolating atmosphere as a powerful mesmerizer, familiar with the properties of the magical agent, can create around him, and no manifestations will take place until some opposing intelligence, more potential than the will-power of the mesmerizer, overcomes the latter and terminates the astral inertia.”
H. P. Blavatsky