When, in 1891, Anton Delbrück[2] published the first comprehensive study of the pathological liar, he not only succeeded in very accurately delineating a more or less distinct psychopathological entity, but also furnished additional proof in substantiation of the fact, well known in psychiatry but as yet unrecognized by the legal profession, that the transition from mental health to mental disease is not a sudden one; that any dividing line which would have for its purpose the strict separation of the mentally sound from the mentally diseased must of necessity be a purely imaginary one, and one not justified by existing facts. The transition from absolute mental health to distinct mental disease is never delimited by distinct landmarks, but shows any number of intermediary gradations. Nowhere is this better illustrated than in the pathological liar. Here one sees how a psychic phenomenon regularly manifested by perfectly normal individuals may gradually acquire such dimensions and dominate the individual to such an extent as to render him frankly insane. To endeavor, however, to definitely state where normality leaves off and disease begins would be, to say the least, to attempt something well-nigh impossible. And yet this is just what the jurist constantly demands of the alienist. The law as it is laid down in the statutes, especially in this country, does not permit of any intermediary stages between mental health and mental disease. An individual, according to law, must either be sane or insane. This point seems to me to be of very vital importance, and I shall have occasion to refer to it again in the consideration of our clinical material. The part played in lying by disturbances of the apprehensive, retentive, and reproductive faculties will not be discussed here in detail. These undeniably have their influence in facilitating the mechanism of lying. But to attribute this phenomenon wholly to disturbances of this nature would be to assign to it a purely passive rôle, whereas experience teaches that back of every lie are active forces, either conscious or unconscious, which give birth to it and determine its type and degree. The following two cases will illustrate better than any formal description could what is meant by pathological lying, a psychopathological state for which Delbrück proposed the term "Pseudologia phantastica":