Page:Popular Science Monthly Volume 13.djvu/67

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solve, as well as from the narrow strip of territory it has subjected to science—the human brain is an organ of very limited capacity.

If some superior being endowed with superhuman, though not necessarily divine powers, should attempt to analyze the mind of man—to assign its relative position in creation, and to place it, properly ticketed and labeled, in some supra-terrestrial museum—it would be found to be a far less imposing object than man's own imagination has pictured it. If it be claimed, as it may be by some, that although this brain has thus far achieved but little, although, whether considered in the aggregate, the average capacity in many nations and through many generations, or, concretely in cases of individual and exceptional genius—as Socrates, Napoleon, Goethe, Newton, Shakespeare—it has fallen so far short of its desires and aims and apparent needs as not to merit the encomiums that poets and philosophers have lavished upon it, yet it has before it in this world, and in our present mode of being, a future of possibly infinite development, I may reply that the study of human testimony is in no way affected by such possibility, since it has to do only with the brain in the past, the present, or the near future.

The whole subject of the limitations of the human brain"[1] is of high import, is very wide in extent, and suggestive practically as well scientifically and in ways almost innumerable, some of which I hope to point out at a future time; but, for the present purpose, the reconstruction of the principles of evidence, it is necessary to refer only to the following illustrations:

  1. The number of distinct thoughts of which the mind is capable in a given time is very limited, and can be estimated by experiment with considerable precision. Says Sir Henry Holland:
    "Within a minute I have been able to coerce mind, so to speak, into more than a dozen acts or states of thought so incongruous that no natural association could possibly bring them into succession. In illustration I note here certain objects which, with a watch before me, I have just succeeded in compressing, distinctly and successively, within thirty seconds of time—the Pyramids of Gizeh, the ornithorhynchus, Julius Cæsar, the Ottawa Falls, the rings of Saturn, the Apollo Belvedere. This is an experiment I have often made on myself, and with the same general result. It would be hard to name or describe the operation of mind by which these successive objects have been thus suddenly evoked and dismissed. There is the volition to change; but how must we define that effort by which the mind, without any principle of selection or association, can grasp so rapidly a succession of images thus incongruous, drawn seemingly at random from past thought and memories? I call it an effort because it is felt as such, and cannot be long continued without fatigue.
    In commenting upon this a writer in Nature says: 'This is a curious subject which easily admits of experiment, but it will be found that the velocity with which thoughts can be made to succeed each other depends entirely upon the degree of similarity or connection between them. Judging from my own experience and that of three students well qualified to test the matter, I find that, where the objects thought of are as incongruous as possible, the number which the mind can suggest to itself in a minute varies from twelve, the result of Sir Henry Holland, up to about twenty. Any one who tries the experiment, however, will find that there is an almost insuperable temptation to go off on lines of association. To avoid these, and yet to think rapidly, requires a very disagreeable effort, becoming more and more painful by repetition. When the thoughts are restricted with-