The author would take to himself the words of Tardieu (“Des attentats aux moeurs”): “Aucune misère physique ou morale, aucune plaie, quelque corrompue qu’elle soit, ne doit effrayer celui qui s’est voué a la science de l’homme et le ministère sacré du médecin, en l’obligeant à tout voir, lui permet aussi de tout dire.”[3] The following pages are addressed to earnest investigators in the domain of natural science and jurisprudence. In order that unqualified persons should not become readers, the author saw himself compelled to choose a title understood only by the learned, and also, where possible, to express himself in _terminis technicis_. It seemed necessary also to give certain particularly revolting portions in Latin[4] rather than in German. It is hoped that this attempt to present to physician and jurist facts from an important sphere of life will receive kindly acceptance and fill an actual hiatus in literature; for, with the exception of certain single descriptions and cases, the literature presents only the writings of Moreau and Tarnowsky, which cover but a portion of the field.[5] TRANSLATOR’S PREFACE. The distinguished author of “Psychopathia Sexualis” speaks for himself and his work in its preface; but there are not wanting others to speak for him. Dr. A. von Schrenck-Notzing, of Munich, writes[6]:— “It may be questioned whether it is justifiable to discuss the anomalies of the sexual instinct apart, instead of treating of them in their proper place in psychiatry. As a rule, they are certainly only symptoms of a constitutional malady, or of a weakened state of the brain, which manifest themselves in the various forms of sexual perversion. “Moreover, attention has been directed to the baneful influence possibly exerted by such publications as ‘Psychopathia Sexualis.’ To be sure, the appearance of seven editions of that work could not be accounted for were its circulation confined to scientific readers. Therefore, it cannot be denied that a pornographic interest on the part of the public is accountable for a part of the wide circulation of the book. But, in spite of this disadvantage, the injury done by implanting knowledge of sexual pathology in unqualified persons is not to be compared with the good accomplished. History shows that uranism was very wide-spread long before the appearance of ‘Psychopathia Sexualis.’ The courts have constantly to deal with sexual crimes in which the responsibility of the accused comes in question.