PREFACE Recent researches in the ethereal realms of Mysticism, Metaphysics,and transcendental Anthropology have proved beyond a doubt the existence of a great number of apparently mysterious and occult facts, whose causes cannot be explained by a science whose means for investigation are limited by the imperfections of sensual perception, and whose researches must necessarily come to a stop where physical instruments cease to be of any service. Invisible things cannot be seen, neither can that which is imponderable be weighed with scales; but invisible and imponderable things, such as the cosmic ether, the lightproducing power of the sun, the vital power of plants and animals, thought, memory, imagination, will, psychological influences affecting the state of the mind or producing a sudden change of feeling, and other things too numerous to mention, are nevertheless facts, and exist in spite of the incapacity of teachers of anatomy or chemistry to explain them. If a reasonable sceptic says that such things do not exist, he can only mean to say that they do not exist relatively to his knowledge ; because, to deny the possibility of the existence of anything of which we know nothing would imply that we imagined ourselves to be in possession of all the knowledge that exists in the world, and believed that nothing could exist of which we did not know. A person who peremptorily denies the

vi PREFACE existence of anything which is beyond the horizon of his understanding because he cannot make it harmonise with his accepted opinions is as credulous as he who believes everything without any discrimination. Either of these persons is not a freethinker, but a slave to the opinions which he has accepted from others, or which he may have formed in the course of his education, and by his special experiences in his (naturally limited) intercourse with the world. If such persons meet with any extraordinary fact that is beyond their own experience, they often either regard it with awe and wonder, and are ready to accept any wild and improbable theory that may be ofifered to them in regard to such facts, or they sometimes reject the testimony of credible witnesses, and frequently even that of their own senses. They often do not hesitate to impute the basest motives and the most silly puerilities to honourable persons, and are credulous enough to believe that serious and wise people had taken the trouble to play upon them "practical jokes," and they are often willing to admit the most absurd theories rather than to use their own common sense. It seems almost superfluous to make these remarks, as perhaps none of our readers will be willing to be classified into either of these two categories; but nevertheless the people to whom they may be applied are exceedingly numerous, and by no means to be found only among the ignorant and uneducated. On the contrary, it seems that now, as at the time of the great Paracelsus, the three (dis)graces of dogmatic science—self-conceit, credulity, and scepticism—go still hand in hand, and that their favourite places of residence are public auditories and the private visiting-rooms of the learned. It is difficult for the light of truth to penetrate into a