It is unfortunately true that most persons are quite unprepared to admit the deficiencies of their own powers of observation and of memory, and are also unaware of their own ignorance of perfectly natural occurrences which continually lead to self-deception and illusion. Moreover, the capacity for logical inference and argument is not common. The whole past and present history of what is called "the occult" is enveloped in an atmosphere of self-deception and of readiness to be deceived by others to which misplaced confidence in their own cleverness and power of detecting trickery renders many--one may almost say most--people victims. The physician who has given his life to the study of mental aberration and diseases of the mind is the only really qualified investigator of these "marvels," and no one who has closely studied what is known in the domain of mental physiology and pathology has any difficulty in understanding, and bringing into relation with large classes of established facts as to illusions and mental aberration, the "beliefs" in magic and second-sight which are here and there found flourishing at the present day, as well as the, at first sight startling, evidence of highly accomplished men who have suffered from such delusions.
Leaving aside all these more extreme cases of what we may call "challenges" to science, let me cite one or two of the more ordinary classes of cases in which science is either attacked or treated with disdain by modern wonder-mongers. It was declared by a writer in the eighteenth century that, after all, human knowledge is a very small thing, since we cannot even tell on one day what the weather is going to be on the next; still less can we control it. That remains perfectly true to-day, although by the hourly observation and record of the movements of "areas of depression" in the atmosphere and the telegraphic communication of these records from all parts of the Atlantic region of the northern hemisphere to central stations, a very important degree of accuracy in foretelling gales, and even minor changes of weather, has been reached. Side by side with this organized study of the movements of "weather" we still have the so-called "almanacs," in which, as in the days of old, certain wizards claim to foretell the weather of a year, as well as other events. It is less surprising that these wizards should find believers when one discovers that there are actually well-to-do, "half-educated" people in England who believe at this day that the delightful clever exhibitors of mechanical tricks and sleight-of-hand are really (as they usually are called) "conjurers"--that is to say, that they conjure spirits and use the "black art." Not long ago, having published my experience of the trickery of "dowsers," and the illusion known as the "divining-rod," I received a letter in which my correspondent related that, being in the coffee-room of an hotel in a country town, he was asked by a man who was there to stretch out his hand. He did so, and the man placed four coppers in a pile upon it. The man then took up an empty matchbox which happened to be on the table, and placed it over the coppers as they lay on my correspondent's hand. After an interval of three or four seconds the man lifted the matchbox, and the coppers were gone! This, which I need hardly say is one of the most common "conjuring tricks" familiar to every schoolboy, was, according to my correspondent, proof to him that the man possessed powers "not dreamed of in your philosophy," and that such powers and those of discovery by use of the divining-rod and similar occult arts are possessed by many gifted beings!