There is every reason to believe that instances of this kind are frequent among persons of a certain temperament, and when such occur in an early period of society, they are almost certain to be considered as real supernatural appearances. They differ from those of Nicolai, and others formerly noticed, as being of short duration, and constituting no habitual or constitutional derangement of the system. The apparition of Maupertuis to Monsieur Gleditsch, that of the Catholic clergyman to Captain C----, that of a late poet to his friend, are of the latter character. They bear to the former the analogy, as we may say, which a sudden and temporary fever-fit has to a serious feverish illness. But, even for this very reason, it is more difficult to bring such momentary impressions back to their real sphere of optical illusions, since they accord much better with our idea of glimpses of the future world than those in which the vision is continued or repeated for hours, days, and months, affording opportunities of discovering, from other circumstances, that the symptom originates in deranged health. Before concluding these observations upon the deceptions of the senses, we must remark that the eye is the organ most essential to the purpose of realizing to our mind the appearance of external objects, and that when the visual organ becomes depraved for a greater or less time, and to a farther or more limited extent, its misrepresentation of the objects of sight is peculiarly apt to terminate in such hallucinations as those we have been detailing. Yet the other senses or organs, in their turn, and to the extent of their power, are as ready, in their various departments, as the sight itself, to retain false or doubtful impressions, which mislead, instead of informing, the party to whom they are addressed. Thus, in regard to the ear, the next organ in importance to the eye, we are repeatedly deceived by such sounds as are imperfectly gathered up and erroneously apprehended. From the false impressions received from this organ also arise consequences similar to those derived from erroneous reports made by the organs of sight. A whole class of superstitious observances arise, and are grounded upon inaccurate and imperfect hearing. To the excited and imperfect state of the ear we owe the existence of what Milton sublimely calls-- The airy tongues that syllable men's names, On shores, in desert sands, and wildernesses.