It is with great diffidence, but under an imperative sense of duty, that the present writer accepts the opportunity afforded him of submitting to his readers some general account of a widespread movement, which, though for the most part treated with ridicule or contempt, he believes to embody truths of the most vital importance to human progress.[1] The subject to be treated is of such vast extent, the evidence concerning it is so varied and so extraordinary, the prejudices that surround it are so inveterate, that it is not possible to do it justice without entering into considerable detail. The reader who ventures on the perusal of the succeeding pages may, therefore, have his patience tried; but if he is able to throw aside his preconceived ideas of what is possible and what is impossible, and in the acceptance or rejection of the evidence submitted to him will carefully weigh and be solely guided by the nature of the concurrent testimony, the writer ventures to believe that he will not find his time and patience ill bestowed.