Few words will be necessary by way of preface to this book, which is designed as an introduction to a little understood and much misrepresented subject. I have not here written anything which is intended to displace the observations of other authors on this subject, nor will it be found that anything has been said subversive of the conclusions arrived at by experimentalists who have essayed the study of clairvoyant phenomena in a manner that is altogether commendable, and who have sought to place the subject on a demonstrable and scientific basis. I refer to the proceedings of the Society for Psychical Research. In the following pages I have endeavoured to indicate the nature of the faculty of Second Sight or Clairvoyance, the means of its development, the use of suitable media or agents for this purpose, and the kind of results that may be expected to follow a regulated effort in this direction. I have also sought to show that the development of the psychic faculties may form an orderly step in the process of human unfoldment and perfectibility.