I have thus presented to the reader, those facts which have afforded, to my own mind, a satisfactory explanation of such relations of spectral appearances, as cannot be refused credit, without removing all the limits and supports of human testimony. To disqualify the senses, or the veracity of those who witness unusual appearances, is the utmost tyranny of prejudice. Yet, who, till within the last fifteen years, would have dared to assert that stones fell from the clouds? Livy had regularly recorded such events, and was ridiculed for supplying those most curious facts, which must otherwise have been lost to natural history. In like manner, I conceive that the unaffected accounts of spectral visions should engage the attention of the philosopher, as well as of the physician. Instead of regarding these stories with the horror of the vulgar, or the disdain of the sceptic, we should examine them accurately, and should ascertain their exact relation to the state of the brain, and of the external senses. The terror of nocturnal illusions would thus be dissipated, to the infinite relief of many wretched creatures; and the appearance of a ghost would be regarded in its true light, as a symptom of bodily distemper, and of little more consequence than the head-ach and shivering attending a common catarrh. There is reason to believe, that many persons suffer silently, from these imaginary visitations, who are deterred from divulging their distresses, by the ridicule with which complaints of this nature are commonly treated. When the proper distinction is established, admitting the reality of the impression, but explaining its production in the mind alone, all difficulties of this kind may be removed, and the apprehensions of the visionary may be readily quieted. Lastly, by the key which I have furnished, the reader of history is released from the embarrassment of rejecting evidence, in some of the plainest narratives, or of experiencing uneasy doubts, when the solution might be rendered perfectly simple. FOOTNOTES: [Footnote 1: The experiments in this Essay appear to have been suggested, by those of Mariotte, Le Cat, and Bernoulli.] [Footnote 2: Zoonomia, Sect. xi. 2.] [Footnote 3: Sect. xi. 8.] [Footnote 4: Voyage d’Islande, in the Ambigu.] [Footnote 5: I subjoin the original account, as it will amuse the reader.