It was in the winter of 1846 that the original seven Letters were written, of which the present fourteen are the third and expanded reprint. The hour had come for successfully assailing certain already shaking prejudices of the reading public. The Selbstschau of Zschokke, and the researches of Von Reichenbach, were in the hands of the literary and philosophic. The seer-gift of the former (see Letter IV.) had established the fact that one mind can enter into direct though one-sided communion with another. The undenied Od-force of the latter (see Letter I.) is evidently the same influence with that, the first crude announcement of which, by Mesmer, had scared the world into disbelief. It had now become possible to explain ghostly warnings, and popular prophecies, the wonders of natural trance, and of animal magnetism, without having recourse to a single unproven principle. I therefore made the attempt; other more efficient labourers have co-operated in the same object; and public opinion is no longer hostile to this class of inquiries. BAD WEILBACH, near MAYENCE, _1st August, 1851_. CONTENTS. LETTER I. THE DIVINING-ROD.—Description of, and mode of using the same—Mr. Fairholm’s statement—M. de Tristan’s statement—Account of Von Reichenbach’s Od-force—The Author’s own observations, 9 LETTER II. VAMPYRISM.—Tale exemplifying the superstition—The Vampyr state of the body in the grave—Various instances of death-trance—The risk of premature interment considered—The Vampyr visit, 30 LETTER III. UNREAL GHOSTS.—Law of sensorial illusions—Cases of Nicolai, Schwedenborg, Joan of Arc—Fetches—Churchyard ghosts, 53 LETTER IV. TRUE GHOSTS.—The apparitions themselves always sensorial illusions—The truth of their communications accounted for—Zschokke’s seer-gift described, to show the possibility of direct mental communication—Second-sight—The true relation of the mind to the living body, 70 LETTER V. TRANCE.—Distinction of esoneural and exoneural mental phenomena—Abnormal relation of the mind and nervous system possible—Insanity—Sleep—Essential nature of trance—Its alliance with spasmodic seizures—General characters of trance—Enumeration of kinds, 86 LETTER VI. TRANCE-SLEEP.—The phenomena of trance divided into those of trance-sleep, and those of trance-waking—Trance-sleep presents three forms; Trance-waking two. The three forms of trance sleep described; viz., death-trance, trance-coma, simple or initiatory trance, 98