De spectris, lemuribus et magnis atque infolities fragoribus, by Ludwig Lavater, 1575.
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Known in English as “Of Ghostes and Spirites Walking by Nyght, and of Strange Noyses, Crackes, and Sundry Forewarnings, Whiche Commonly Happen Before the Death of Menne, Great Slaughters, & Alterations of Kyngdomes,” from the 1572 English translation, this book is one of the most important demonological works of the Reformation era and was profoundly influential in Elizabethan literature. The author, Ludwig Lavater (1527-1886), was a Swiss Zwinglian minister and theologian based in Zurich. In the 16th and 17th-century Protestant world, new questions surfaced regarding the nature of ghostly apparitions—particularly their origins. In the Catholic understanding, ghosts were generally thought to be spirits of the dead on leave from Purgatory. With their rejection of the doctrine of Purgatory, Protestant philosophers and theologians were compelled to search for new answers.