I care naught for public opinion: not that I disdain it—on the contrary, I have the greatest respect for its judgment—but I am not addressing the public. The question I am studying is not ripe for the public; or the case may be the other way about. I address those brave men of whom I have just spoken, to let them know I am of their mind, and that _my_ observations confirm theirs on many points. I also address those who are seeking to establish the reality of the curious phenomena, treated of in this book. I have tried to fill a gap by showing them the best methods to adopt, in order to arrive at appreciable results,—such results being far less difficult to obtain than is commonly supposed. A word about the method I have followed. I have purposely refrained from giving a purely scientific aspect to my book, though I might have done so had I chosen, for the usual scientific dressing is unsuitable to the subject in hand. It seemed preferable to relate what I have seen, leaving it to those for whom I write to believe me or not, as they think fit. I might have accumulated not a little testimony and considerable external evidence, but to have done so would not have been the means of convincing a single extra reader. Those, whom my simple affirmation leaves sceptical, would not be convinced by reports signed by witnesses, whose sincerity and competence are frequently called into question. Neither did I wish to adopt the method followed by the Agnélas, Milan, and Carqueiranne experimenters, in giving a detailed report of all my sittings; this method too has its advantages and disadvantages. However exhaustive a report may be, it is difficult to indicate therein all the conditions of the experiment; oversights are inevitable. Moreover, it would be useless to say that every precaution had been taken against fraud, for in enumerating such precautions, the omission of a single one would suffice to expose oneself to most justifiable criticism. Probably that very precaution was elementary and had been taken, or was considered useless and put aside deliberately; nevertheless such circumstances would not escape criticism. We wish to convince by pointing out the exact conditions of the experiment; but those, whom we would most wish to convince, are the very persons least prepared to judge of the conditions in which psychical experiences are obtained. These are physicists and chemists; but living matter does not react like inorganic matter or chemical substances. I do not seek to convince these savants; my book is unassuming and makes no pretence of having been written for them. If they in their turn should be tempted to try for those effects which I have obtained, the methods indicated will be easily accessible to them. It is in this way they can be indirectly convinced, though to convince them is not my present aim. Others are better qualified than I am to try their hand at this most desirable but, for the moment, most difficult task.