The encounter between modern rationalism and otherness is the central theme of fantastic literature: in the ordinary, everyday world, a sudden and extraordinary phenomenon shatters "the natural order of things" in a few seconds. Caillois defined this sudden tearing of the real: «irruption of the inadmissible». Thus, the first condition of the fantastic is, as Todorov says, "the reader's doubt." Well, the curious thing about the case is that each of these characteristics of the fantastic tale can very well be applied to a good part of the "stories" in this book, by also proposing a radical displacement of meaning in reality, albeit with a notable difference: here «the fantastic» does not occur on the stage of literary fictions, but in the historical field, in the real world, as evidenced by the documentary sources, which can be consulted at the end of the volume. Only the reader will be able to judge if everything that these pages refer to is just a more or less literary story, or the slight rumor of an unknown reality; in short, the old dilemma of fantastic literature.

This book is not about the interpretation of dreams, it explores the different meanings that the verb to dream has in relation to history, the sacred, the inner dimensions of consciousness, the paradoxes and complexities of time, and the poignant enigma of death. In the first chapter, certain dreams (of Hannibal, Von Bismarck, Lincoln, Perpetua or Descartes, among others) demand a new historical category: the oneiric. The second chapter tries to explain what dream incubation consisted of in ancient healing temples. The third is a brief history of lucid dreaming. The fourth delves into the labyrinths of dream time, giving special emphasis to the paradoxical dreams that make the future present. The last one is an investigation into the metaphor of sleep and its correspondence with death, into the oneirism of the dying and into the scientific and mystical visions of otherness.