I
The possibility of the transference of thought, apart from the recognized channels of sensation, has been too frequently discussed, with the suppressed or unconscious assumption that our knowledge of the means whereby we ordinarily and normally, consciously and unconsciously, convey to others some notion of what is passing in our own minds, is comprehensive and exhaustive. Nothing could be farther from the truth. Whenever a mode of perception, no matter how limited or apparently trivial, has been thoroughly investigated, there have been discovered, or at least suggested, unrecognized possibilities of its use and development. And no result of experimental inquiry is more constantly illustrated than the extent to which inferences from sensations and the exercise of faculties may proceed without arousing consciousness of their existence. Many color-blind persons remain quite ignorant of their defect; and it was only after the description of his own notable deficiencies by Dalton (in 1794) that the general prevalence of color-blindness became recognized. The fact that a portion of every one's retina is as blind as his finger-tip escaped observation until about two centuries ago; and this because the normal use of our eyes does not present the conditions of its easy detection; and for a like reason we persistently refuse to see the double images that are constantly formed upon our retinæ. With the same unconsciousness that we receive sensations and draw inferences from them, do we give to others indications of what is going on in our minds, and read between their words and under their expressions what "half reveals and half conceals the thoughts that lie within." It is important to emphasize the serious limitations as yet attaching to our knowledge of the detailed possibilities of normal perception and inference, in order to realize the corresponding hesitancy with which we should regard any series of facts, no matter how apparently inexplicable, as evidence of a supernormal kind of mental telegraphy.
A further principle important in this connection, and one which is likewise borne out by experimental inquiry, is the general similarity in our mental machinery in matters great and small, and the resulting frequency with which similar trains of thought may be carried on by different persons as the outcome of similar but independent brain-functioning. There is a natural tendency to exaggerate the individuality of our own ways of thought and expression; and yet but little reflection is necessary to suggest how easily this fond belief may be at least partially delusive. In certain lines of thought, such as mathematics, we should regard it as strange if two thinkers, starting with the premises determined by the problem in hand, should not reach the same conclusion; in others, such as economic or political questions, we observe the preponderance of evidence in one direction, and yet can appreciate the grounds of a contrary opinion; and while in still other cases we regard the verdict as a matter of taste or of individual preference, it may be questioned whether this is so unmotived or lawless a process as is commonly assumed. While we properly expect more mental community in certain lines than in others, we have good grounds for believing that it exists everywhere and only awaits the proper modes of investigation to reveal it in its full extent and significance. With the marvelously increased facilities for the dissemination and transportation of thought, the range of such mental community is certain to be correspondingly extended. Coincidences arising from the bringing together of widely separated and apparently unrelated happenings are sure to multiply, when the means of bringing them together are so vastly increased. Each man's world is enlarged by the enlargement of the whole. It becomes possible for him to come into relation with infinitely more persons and events, and the resulting coincidences are nowadays more likely to be noticed and recorded.
If we consider the logical ease with which the successful solution of one portion of a problem suggests the next step; how imperceptibly and yet effectively sentiments and points of view and the spirit of the time are disseminated; how many persons there are in this busily reflective era occupied with similar thoughts and schemes, and how readily they may come into communication; how many are anxiously studying the popular taste and demand to determine what literary venture or mechanical invention is likely to be timely and successful; how the possession of a common inheritance, patriotic interests, education, literature, political arena, social usages, newspaper intelligence, household conveniences, and the endless everyday factors of our complex, richly detailed existence all contribute to our common life,—shall we wonder that some two or half a dozen intellects should give expression to similar thoughts at nearly the same time? Would it not be infinitely more wonderful if such coincidences did not constantly occur? In the more original contributions to literature, science, and inventions, such thought-correspondences should be rarer; and certainly this is true. Contrast the number of striking similarities in the higher walks of literature and science with those that occur in small inventions. Hardly a day passes without the coincidence of two persons thinking of devices for accomplishing the same purposes, so essentially similar that patents could not be given to both. It is certainly not difficult to understand why several different patterns of typewriting machines should be invented nearly simultaneously, and it would not be altogether mysterious if, at the first, two inventors had independently reached the idea of a writing-machine at nearly the same time. The experience of offering an article to an editor and receiving a reply to the effect that another article dealing with a similar topic in a similar way was already awaiting the compositor is not unusual. It is true that these coincidences are of a minor order, but it seems desirable to emphasize the frequency of these minor forms in order to suggest the law-abiding character of the rarer or the more striking forms; for this is just what the normal distribution of such phenomena would lead us to expect.
It would be pleasant to believe that the application of the doctrine of chances to problems of this character is quite generally recognized; but this recognition is so often accompanied by the feeling that the law very clearly applies to all cases but the one that happens to be under discussion, that I fear the belief is unwarranted. Moreover, the notion seems to prevail that these coincidences should occur with equal frequency to all persons; while, in fact, the law of probability provides for the most various distribution among individuals. However, the attempt, and it may be the sincere attempt, to apply proper conceptions of probability and improbability to such problems often fails, because of an unfortunate mental attitude which presents, with an outward acquiescence in the objective view of the problem, an inward conviction in which the subjective interpretation is really dominant; for this and other reasons, this objective method of viewing the matter, however pertinent, is not the most important.