INTRODUCTION 1 My Essay on Death led me to make a conscientious enquiry into the present position of the great mystery, an enquiry which I have endeavoured to render as complete as possible. I had hoped that a single volume would be able to contain the result of these investigations, which, I may say at once, will teach nothing to those who have been over the same ground and which have nothing to recommend them except their sincerity, their impartiality and a certain scrupulous accuracy. But, as I proceeded, I saw the field widening under my feet, so much so that I have been obliged to divide my work into two almost equal parts. The first is now published and is a brief study of veridical apparitions and hallucinations and haunted houses, or, if you will, the phantasms of the living and the dead; of those manifestations which have been oddly and not very appropriately described as "psychometric"; of the knowledge of the future: presentiments, omens, premonitions, precognitions and the rest; and lastly of the Elberfeld horses. In the second, which will be published later, I shall treat of the miracles of Lourdes and other places, the phenomena of so called materialization, of the divining-rod and of fluidic asepsis, not unmindful withal of a diamond dust of the miraculous that hangs over the greater marvels in that strange atmosphere into which we are about to pass.  Published in English, in an enlarged form, under the title of Our Eternity (London and New York, 1913)—Translator's Note. 2 When I speak of the present position of the mystery, I of course do not mean the mystery of life, its end and its beginnings, nor yet the great riddle of the universe which lies about us. In this sense, all is mystery, and, as I have said elsewhere, is likely always to remain so; nor is it probable that we shall ever touch any point of even the utmost borders of knowledge or certainty. It is here a question of that which, in the midst of this recognized and usual mystery, the familiar mystery of which we are almost oblivious, suddenly disturbs the regular course of our general ignorance. In themselves, these facts which strike us as supernatural are no more so than the others; possibly they are rarer, or, to be more accurate, less frequently or less easily observed. In any case, their deep-seated cause, while being probably neither more remote nor more difficult access, seem to lie hidden in an unknown region less often visited by our science, which after all is but a reassuring and conciliatory espression of our ignorance. Today, thanks to the labours of the Society for Psychical Research and a host of other seekers, we are able to approach these phenomena as a whole with a certain confidence. Leaving the realm of legend, of after-dinner stories, old wives' tales, illusions and exaggerations, we find ourselves at last on circumscribed but fairly safe ground. This does not mean that there are no other supernatural phenomena besides those collected in the publications of the society in question and in a few of the more weighty reviews which have adopted the same methods. Notwithstanding all their diligence, which for over thirty years has been ransacking the obscure corners of our planet, it is inevitable that a good many things escape their notice, besides which the rigour of their investigations makes them reject three fourths of those which are brought before them. But we may say that the twenty-six volumes of the society is Proceedings and the fifteen or sixteen volumes of its Journal, together with the twenty-three annuals of the Annales des Sciences Psychiques, to mention only this one periodical of signal excellence, embrace for the moment the whole field of the extraordinary and offer some instances of all the abnormal manifestations of the inexplicable. We are henceforth able to classify them, to divide and subdivide them into general, species and varieties. This is not much, you may say; but it is thus that every science begins and furthermore that many a one ends. We have therefore sufficient evidence, facts that can scarcely be disputed, to enable us to consult them profitably, to recognize whither they lead, to form some idea of their general character and perhaps to trace their sole source by gradually removing the weeds and rubbish which for so many hundreds and thousands of years have hidden it from our eyes.