two or three years since by Mr. Edison, the renowned inventor of the phonograph. This claim belonged primarily to physics, and secondarily to physiology, and was carefully investigated by many physicists and some physiologists of this country and Europe, and by them it was decided, rightly or wrongly, that the claim was not proved, that the spark supposed to indicate a new force represented a hitherto undetected phase of induced electricity.
IV. Claims which, from the limitations of the human faculties, can never be proved or disproved.
Claims of this kind may be indulged in as speculations, with the understanding that they are merely speculations; but to seriously discuss them, with the purpose of ascertaining their truth or falsity, is unscientific.
Under this head all supernatural claims must be included, for the reason that it is impossible for the human faculties to distinguish between what is unknown in Nature and what is above Nature. The narrow limitations of our knowledge of Nature all will admit. What expert professes to exhaustively know Nature even in his own department? What, indeed, is all our knowledge but an infinitesimal fraction of our ignorance; a flower or so plucked from a boundless garden; a few ores dug from measureless mines; a slight clearing in an infinite wilderness; "a film on the ocean of the unknown?" Leaving out of view all questions of supernaturalism and all the phenomena of life, what do we know, or, in this world, have we reason to expect to know, of inorganic Nature? What is light? What is heat? What is gravity? Why should one mode of motion make one form of force and not another? Toward the solution of these primal questions—that the infant can ask and the philosopher cannot answer—the sciences and reasoning of all the centuries have made, and are destined to make, no advance.
Even if an expert could be supposed who should exhaustively know Nature in his own department, how could he know that he knew it? Not knowing that he knew all Nature in his own realm, what tests would he have—could he have—to distinguish between the supernatural and what might be unknown in Nature? If, to go to the outermost verge of conceivability for illustration, the clock of the universe were turned back to-morrow, and the sun should thereafter rise in the west instead of the east, how would it be possible to prove, in a scientific sense, that a supernatural event had occurred?
Every phenomenon that can be brought to the attention of the human faculties must be referred to one of these three classes:
1. The known in Nature.
2. The unknown in Nature.
- Mr. Edison's views, as he writes me, are unchanged. His experiments, and my own made in cooperation with him, as well as a discussion of the bearings of the claim on the principles of evidence, were published two years since.