The properties which differentiate living matter from any kind of inorganic imitation may be instinctively felt, but can hardly be formulated without expert knowledge.
In other cases, when the medium becomes entranced, the demonstration of a communicator's separate intelligence may become stronger and the sophistication less.
The hypothesis of surviving intelligence and personality - not only surviving but anxious and able with difficulty to communicate - is the simplest and most straightforward and the only one that fits all the facts.
We know that communication must be hampered, and its form largely determined, by the unconscious but inevitable influence of a transmitting mechanism, whether that be of a merely mechanical or of a physiological character.