shapes,[1] of their departed friends—it is perfectly conformable to scientific probability that they should pass more or less completely (like Reichenbach's "sensitives") into a state which is neither waking nor sleeping, but between the two, in which they see, hear, or feel, by touch, anything they have been led to expect will present itself. And the accordance of their testimony, in regard to such occurrences, is only such as is produced by the community of the dominant idea with which they are all "possessed," a community of which history furnishes any amount of strangely-varied examples. And thus it becomes obvious that the testimony of a single cool-headed skeptic, who asserts that nothing extraordinary has really occurred, should be accepted as more trustworthy than that of any number of believers, who have, as it were, created the sensorial result by their anticipation of it.
I have now to show you that the like expectancy can also produce movements of various kinds, through the instrumentality of the nervo-muscular apparatus, without the least consciousness on the part of its subject of his being himself the instrument of their performance; a physiological fact which is the key to the whole mystery of table-turning and table-talking. I very well remember the prevalence in my schoolboy days of a belief that, when a ring, a button, or any other small body, suspended by a string over the end of the finger, was brought near the outside or inside of a glass tumbler, it would strike the hour of the day against its surface; and the experiment certainly succeeded in the hands of several of my schoolfellows, who tried it in all good faith, getting up in the middle of the night to test it, in entire ignorance, as they declared, of the real time. But, as was pointed out by M. Chevreul, who investigated this subject in a truly scientific spirit more than forty years ago,[2] it is impossible by any voluntary effort to keep the hand absolutely still for a length of time in the position required; an involuntary tremulousness is always observable in the suspended body, and if the attention be fixed on it with the expectation that its vibrations will take a definite direction, they are very likely to do so. But their persistence in that direction is found to last only so long as they are guided by the sight of the operator, at once and entirely losing their constancy if he closes or turns away his eyes. Thus it became obvious that, in the striking of the hour, the influence which determines the number of strokes is really the knowledge or suspicion present to the mind of the operator, which involuntarily and unconsciously directs the action of his muscles; and the same rationale was applied by M. Chevreul to other cases in which this pendule explorateur (the use of which can be traced
