The nerve cells appear to possess, beyond the simple excitability to general stimuli, conductility, and the peculiar receptivity which is essential to sensation, a special or more exalted kind of excitability which is called into play under mental or psychical stimuli by the changes produced in the gray matter[5] in the formation of ideas, emotions, and the will.[6]
Now if two sympathetic nerve systems operated upon by psychical stimuli be directed to one and the same point, it is by no means difficult to understand how the brains belonging to those systems may be brought into telegraphic communication by means of the nerve fibres, the product of the two minds evolved, and the resultant idea, by means of a simple mechanical contrivance operated upon by the motor function already explained, be transmitted to paper by the process of writing so familiar to both. The action of the psychical stimuli on the nerve fibre, and its transmission thence to the muscles resulting in the movement of the board, is so subtle that we ourselves are not aware of its operation except through the results produced.
It has just been said that two minds may be brought into telegraphic communication by means of nerve fibres. Let us see how far the expression is justified by facts. There are few of us who have not experienced the truth of Solomon's saying that "if two persons lie together, they have heat; but how can one be warm alone?" Even the close proximity of two persons affects their respective temperatures, and heat and motion we know to be correlative. It has been shown by the physicist that mechanical force producing motion is correlative with and convertible into heat, heat into chemical force, chemical force into electrical force, and electrical force into magnetic force. Moreover, that each of these is correlative and convertible into the other, all being thus interchangeable.
"Now it is not to be supposed that the force acting in a nerve is identical with electrical force, nor yet a peculiar kind of electricity, nor even physically induced by it, as magnetism may be, but that in the special action of the living nerve a force is generated peculiar to that tissue, which is so correlated with electricity that an equivalent of the one may in some yet unknown manner excite, give rise to, or even be converted into the other. In this concatenation of the several forces of nature, physical and vital, the force acting in a nerve may also be correlated with chemical force, with the heat developed in the muscle, and even with the peculiar molecular motions which produce muscular contraction and all its accompanying physical and mechanical consequences." If, then, two brains, one in London and one in New York, may be brought into communication with each other through their respective nerve systems and the common medium of the electric wire, and both brought to bear on one idea—say the rate of exchange, consols, or the price of gold—is it to be wondered at that two other brains, in close proximity, may be brought into communication through the media of the nerve fibres which are operated upon by a force so similar to that which courses along the electric wire? Or is it strange that the two sympathetic minds—two minds having a strong affinity for each other—should combine and generate ideas? and having produced them, is it strange they should give them expression in writing? Before the days of Franklin, this might indeed appear strange, but it surely cannot be so considered now.
Such, then, is the rationale of what may be termed the automatic writing, by means of Planchette, and such writing is simply a manifestation of what has been named psychic force. Whether operated by one or two persons, the rationale is the same.
There is reason to believe that the phenomenon just explained was known to the ancients, and that it was the origin of the oracles which formed so important a feature, at one period, in the history of Greece; such, for example, as the "Whispering Groves of Dodona," and the yet more famous oracle of Delphi.[7] It is worthy of remark that these oracles were not established at the first by the Greeks themselves. They were of foreign origin, having been first introduced from Egypt, then the seat of learning.
The secret of psychic force having been once discovered, it may easily be conceived how it would be seized upon as a means of communicating, as the pagans supposed, with beings of another world, and how readily the more enlightened and designing would avail themselves of it as a means to practise upon the credulity of a superstitious people. Such were the cunning priesthood in the temples of pagan worship. They were quick to take advantage of a discovery that offered so powerful a leverage, and having once secured its services, they did not scruple to shape the utterances to suit their own selfish ends. Frequently their answers were so framed as to admit of a double interpretation.
Crœsus consulted the oracle of Delphi on the success that would attend his invasion of the Medes. He was told that by passing the river Halys a great empire would be ruined. He crossed, and the fall of his own empire fulfilled the prophecy. Sometimes they were couched in vague and mysterious terms, leaving those who solicited advice to put whatever construction upon them their hopes or fears suggested. Compare, for example, the first specimen of writing given in this article with the descriptions we read in ancient history of the utterances of the Delphic oracle. How vague and indefinite are its warnings! and then the continual recurrence of the solemn admonition, "Hope and trust"—does it not seem prophetic of some evil hour, when all one's hope and faith were to be tried to the utmost?
Suppose these words had been addressed to a superstitious person by the priestess of a temple situated in the deep recesses of a dense forest, among the toppling crags of some lofty mountain range, or near the gloomy habitations of the dead: it could not have failed of making a serious impression upon the mind. It was thus that the pagan priesthood threw about their oracles everything that could inspire the mind of the visitor with a sense of awe. We are told that the "sacred tripod" was placed over the mouth of a cave whence proceeded a peculiar exhalation.
On this tripod sat the Pythia—the priestess of Apollo—who, having caught the inspiration, pronounced her oracles in extempore prose or verse. The cave and the exhalations were mere accessories, stage properties as it were, the more readily to impose upon those who came to consult the oracle. So of the "sacred tripod," which was the symbol merely of the real instrument which had given birth to this system of fraud.