6i4 THE POPULAR SCIENCE MONTHLY. 



through the involuntary life — the mind of the subject acting on the 

 body — and producing results which, it is to be noted, are as decided, as 

 uniform, and as permanent as when produced by powerful objective 

 influences. This element of error slips into all the ordinary experi- 

 ments with new remedies and supposed new forces in the animal body, 

 thus corrupting science at its very sources. The neglect of this 

 element of error would of itself, even though all the other errors were 

 guarded against, destroy entirely the scientific value of all such experi- 

 ments, for example, as those of the committees of the French Academy 

 with clairvoyants and mesmerism ; it is because physicians of experi- 

 ence instinctively feel this element of error, that reports of cases 

 wrought by novel and strange and especially by imposing methods of 

 treatment are so frequently discredited. Under this head come also 

 all the so-styled miracles of healing, whatever may be the paraphernalia 

 through which they are accomplished. 



I know not where can be found a better single illustration of the 

 effect of this element of error, alone of itself, in scientific research, 

 when all the other elements of error seem to be provided for, than in 

 the experiments on animal magnetism of the late Dr. J. K. Mitchell, as 

 recorded in the volume of his miscellaneous writings. Dr. Mitchell 

 was an original thinker, an observer of patience and care, and a clear 

 and logical writer, who suggested more than he told, and his chapter on 

 animal magnetism was incomparably the best essay ever written on that 

 subject down to the date of its publication. This paper — which con- 

 sisted of a record of independent, careful, and many times repeated 

 experiments on living human beings, witli remarks thereon — shows that 

 the author not only had the courage and the power to do his own think- 

 ing and experimenting, but that he recognized some of the chances of 

 error in experiments of this kind, and fortified himself against them ; 

 while of the errors that enter through the doors of the involuntary life — 

 the unconscious deception of the subject experimented on — he knew, 

 and apparently suspected, little. His essay is therefore at once a 

 model and a warning : a model for thoroughness and precision up to a 

 certain point, or within a limited area ; a warning as demonstrating the 

 worthlessness of all experiments with human beings when any one or 

 two of the six sources of mistake are overlooked. So accurate and 

 scientific were these experiments, in certain directions, that they have 

 furnished an important contribution to our knowledge of some of the 

 symptoms of mesmerism, in spite of the fact that the author failed, 

 like hundreds of able men in science before him, to solve the problem 

 of the nature of trance. By not understanding and taking into account 

 the phenomena of the involuntary life, of which in his day very little 

 was known, and of trance, of which nothing was known, this acute and 

 philosophic observer allowed the subjects on whom he operated to con- 

 stantly deceive themselves and deceive him, and to drive him to the 

 logical but absolutely false conclusion that the mesmeric trance was an 



