I have given this lengthened extract from Zimmerman, because I think it satisfactorily explains those mystic _visions_ as well as _infernal phantoms_, with which the mediæval legends and chronicles, generally composed by monks, abound, and which are often unjustly ascribed to fraud and wilful deception. Medical science, as well as all the branches of natural philosophy, being then in a very imperfect condition, such phenomena as those of nuns mewing like cats or biting like dogs, which are mentioned by Zimmerman, were not explained as nervous diseases, but ascribed to the possession of evil spirits; and I frankly confess that I am by no means sure, that if cases like those mentioned above were to happen in our enlightened age, there would not be found many good folks ascribing them to a similar agency. It must be also remembered that, if notwithstanding the extreme rapidity and regularity of communications in our own time, reports of various events are often exaggerated and even completely altered in passing from one place to another; how much more must it have been the case during the time of such defective communication as existed previous to the invention of printing and the introduction of the post! It was therefore no wonder if occurrences of such an extraordinary nature as those alluded to were immensely magnified by report, and if it had, at least in many places, converted the mewing and biting nuns into as many cats and dogs. It is, moreover, now generally admitted that what is called mesmerism, but whose real nature science has not yet explained, was known and practised during the middle ages, as well as in remote antiquity, and that many thaumaturgic operations, described by the mediæval legends, as well as by ancient writers, were produced by means of this still mysterious agency. I have dwelt perhaps too long on this subject, because I am afraid that the observations relating to it are not confined to a distant period, but may become but too often applicable to our own times. And, indeed, when we reflect on the rapid increase of convents and nunneries, particularly in this country, and that notwithstanding the present state of civilization these establishments must be filled chiefly by individuals whose imaginations are stronger than their reasoning powers, there can be little doubt that they may again become the stage of those extraordinary manifestations, the cause of which had been too exclusively ascribed to mediæval darkness. It cannot be doubted, that designing individuals of both sexes, possessed of superior talents and knowledge, but particularly endowed with a strong will, may exercise not only an undue influence, but even an absolute power over the inmates of the above-mentioned monastic establishments; and that a skilful application of mesmerism may efficiently promote such unlawful ends.