Not only is it possible for a single individual to be deceived by mistaking subjective for objective impressions, but, as 1 have proved by repeated experiments, the details of which have already been published, it is possible and easy to cause a large number of individuals, of intelligence and in good health, to see simultaneously the same subjective visions without any of them being able to detect the deception. Such experiences of the simultaneous confounding of the subjective with the objective are not exceptional to the degree that we might suppose; they are frequently occurring, and can be verified without difficulty by those who are trained to the art of experimenting with living human beings. All situations and experiences that excite the emotions of awe, of wonder, or reverence, or fear, or expectation, either singly or in combination, are liable to produce subjective visions that may appear at the same time and in the same form to large numbers of people, not one of whom shall be able, without external aid, to recognize the deception; and when these various emotions, powerfully aroused, do not thus cause impressions to be absolutely originated on the retina, they may, and often do, so modify the impressions made by objects to which the eyes and the attention are directed as to give rise to delusions that are both absolute and absurd, and out of which the subjects, though perfectly sane and sound, and, it may be, also scholarly, and accomplished, and scientific, can never be reasoned.
Delusions from this cause are in part, though not entirely, the origin of the myths, the legends, and the traditions, of what is called history, and are constant and oftentimes fatal elements of error in all historical criticism. The science of history will never attain the precision of which it is capable until the chaff of the subjective is winnowed from the wheat of the objective; until it is recognized as a physiological and pathological fact that the seeing of any object by any number of honest and intelligent people is no necessary evidence of the existence of that object; and, until it is understood that the claims of what is seen by individuals or by multitudes, all concurring in their testimony, are to be determined, if determined at all, only by reasoning deductively from the known circumstances under which the claims were made, and from general principles of science previously established. Yet further, it must be under-
- Gibbon's "History of the Decline and Fall of the Roman Empire," for example, contains a vast number of statements and discussions which, scientifically, are of no value, and indeed by no manner of possibility could have any value. Details of expressions and actions, which, when obtained directly from the authors, must have been largely untrue, become, when filtered down the centuries through armies of non-experts, but the counterfeit of human experience—a satire on history. The historical writings of Prescott and of Irving are especially open to this criticism, and should be commended to the young with the suggestion, always, that they are to be considered as fiction; indeed, the best novels are better histories than much of professed history, since they do not attempt the impossible burden of carrying exact details, but merely aim to teach general facts, principles, and events, concerning which a certain degree of truth is sometimes attainable.
A volume of historical criticism is suggested by the following admission of Carlyle in