Even the most enthusiastic advocate of the present state of knowledge cannot maintain that it is perfect. On the contrary, he will recognise that an advance of the barriers that separate that which is now understood from what is not understood, is not only possible, but even on his part devoutly to be wished. Indeed, a very large province of knowledge—that of superstition—still remains almost wholly unworked. It is absurd to imagine that all the tales of magic and demonology are founded entirely in deception. For how could it happen that in all historical epochs, and among all the peoples of the earth, the same phenomena should be uniformly reported, if something true and real were not concealed behind it all! The illuminate, of course, looking upon our present code of ideas as ultimate, shrugs his shoulders with a superior air and banishes what to him is "supernatural" into the realm of fables; the cautious observer, on the other hand, refrains from passing judgment thus prematurely, for he knows that departments formerly very extensive have passed out of the realm of superstition into the kingdom of science, and that in the future the same will also occur. Thus the divine summons in the mediæval trial by ordeal have turned out to be effects of suggestion, and the majority of the performances of witches have proved to be the effects of hysterical temperament. So that we are now in a position to comprehend the tales of the Magic Mirror[25] in their true light and to bring them, without constraint, into accord with the doctrines of a developed science of psychology. [25] The Japanese "Magic Mirrors" consist of ingenious physical contrivances and are in no way concerned with our present subject.