I have shewn that a morbid disposition of the brain is capable of producing spectral impressions, without any external prototypes. The religion of the ancients, which peopled all parts of nature with deities of different ranks, exposed them, in a peculiar manner, to delusions of the imagination; and I have had occasion, in another essay,[17] to mention the influence which the doctrines of Plato have exerted, in this respect, even since the establishment of christianity. From recalling images by an art of memory, the transition is direct to beholding spectral objects, which have been floating in the imagination. Yet, even in the most frantic assemblage of this nature, no novelty appears. The spectre may be larger or smaller; it may be compounded of the parts of different animals; but it is always framed from the recollection of familiar, though discordant images. The simple renewal of the impressions of form or voice, in the case of particular friends, is the most obvious, and most forcible of these recollections. Of this kind, seems to have been the celebrated apparition of Ficinus, to Michael Mercato, mentioned by Baronius. Those illustrious friends, after a long discourse on the nature of the soul, had agreed that, whoever of the two should die first, should, if possible, appear to his surviving friend, and inform him of his condition in the other world.[18] A short time afterwards, says Baronius,[19] it happened, that while Michael Mercato the elder was studying philosophy, early in the morning, he suddenly heard the noise of a horse galloping in the street, which stopped at his door, and the voice of his friend Ficinus was heard, exclaiming, O Michael! O Michael! those things are true. Astonished at this address, Mercato rose and looked out of the window, where he saw the back of his friend, drest in white, galloping off, on a white horse. He called after him, and followed him with his eyes, till the appearance vanished. Upon inquiry, he learned that Ficinus had died at Florence, at the very time when this vision was presented to Mercato, at a considerable distance. Many attempts have been made to discredit this story, but I think the evidence has never been shaken. I entertain no doubt, that Mercato had seen what he described; in following the reveries of Plato, the idea of his friend, and of their compact, had been revived, and had produced a spectral impression, during the solitude and awful silence of the early hours of study. Baronius adds, that after this occurrence, Mercato neglected all profane studies, and addicted himself entirely to divinity. The vanishing of the imaginary apparition, in these cases, resembles Achilles’s vision, in the Iliad. ----ψυχὴ δὲ κατὰ χθονὸς ἠΰτε καπνὸς ᾤχετο τετριγυῖα.---- The impression of sound, the most remarkable circumstance in Mercato’s vision, is by no means a solitary instance. Beaumont has given us, not only his own ghostly experience, but many examples of this species of delusion.