Yet, although we are, on every hand, surrounded by the normal manifestations of sex, conscious or unconscious, these manifestations are extremely difficult to observe, and, in those cases in which we are best able to observe them, it frequently happens that we are unable to make any use of our knowledge. Moreover, even when we have obtained our data, the difficulties--at all events, for an English investigator--are by no means overcome. He may take for granted that any serious and precise study of the sexual instinct will not meet with general approval; his work will be misunderstood; his motives will be called in question; among those for whom he is chiefly working he will find indifference. Indeed, the pioneer in this field may well count himself happy if he meets with nothing worse than indifference. Hence it is that the present volume will not be published in England, but that, availing myself of the generous sympathy with which my work has been received in America, I have sought the wider medical and scientific audience of the United States. In matters of faith, "liberty of prophesying" was centuries since eloquently vindicated for Englishmen; the liberty of investigating facts is still called in question, under one pretence or another, and to seek out the most vital facts of life is still in England a perilous task. I desire most heartily to thank the numerous friends and correspondents, some living in remote parts of the world, who have freely assisted me in my work with valuable information and personal histories. To Mr. F.H. Perry-Coste I owe an appendix which is by far the most elaborate attempt yet made to find evidence of periodicity in the spontaneous sexual manifestations of sleep; my debts to various medical and other correspondents are duly stated in the text. To many women friends and correspondents I may here express my gratitude for the manner in which they have furnished me with intimate personal records, and for the cross-examination to which they have allowed me to subject them. I may already say here, what I shall have occasion to say more emphatically in subsequent volumes, that without the assistance I have received from women of fine intelligence and high character my work would be impossible. I regret that I cannot make my thanks more specific. HAVELOCK ELLIS. CONTENTS. THE EVOLUTION OF MODESTY. I. The Definition of Modesty--The Significance of Modesty--Difficulties in the Way of Its Analysis--The Varying Phenomena of Modesty Among Different Peoples and in Different Ages. II.