It appears to have been largely due to Griesinger, in the middle of the last century, that we owe the first authoritative appearance of a saner, more discriminating view regarding the results of masturbation. Although still to some extent fettered by the traditions prevalent in his day, Griesinger saw that it was not so much masturbation itself as the feelings aroused in sensitive minds by the social attitude toward masturbation which produced evil effects. "That constant struggle," he wrote, "against a desire which is even overpowering, and to which the individual always in the end succumbs, that hidden strife between shame, repentance, good intentions, and the irritation which impels to the act, this, after not a little acquaintance with onanists, we consider to be far more important than the primary direct physical effect." He added that there are no specific signs of masturbation, and concluded that it is oftener a symptom than a cause. The general progress of educated opinions since that date has, in the main, confirmed and carried forward the results cautiously stated by Griesinger. This distinguished alienist thought that, when practiced in childhood, masturbation might lead to insanity. Berkhan, in his investigation of the psychoses of childhood, found that in no single case was masturbation a cause. Vogel, Uffelmann, and Emminghaus, in the course of similar studies, have all come to almost similar conclusions.[323] It is only on a congenitally morbid nervous system, Emminghaus insists, that masturbation can produce any serious results. "Most of the cases charged to masturbation," writes Kiernan (in a private letter), basing his opinion on wide clinical experience, "are either hebephrenia or hysteria in which an effect is taken for the cause." Christian, during twenty years' experience in hospitals, asylums, and private practice in town and country, has not found any seriously evil effects from masturbation.[324] He thinks, indeed, that it may be a more serious evil in women than in men. But Yellowlees considers that in women "it is possibly less exhausting and injurious than in the other sex," which was also the opinion of Hammond, as well as of Guttceit, though he found that women pushed the practice much further than men, and Näcke, who has given special attention to this point, could not find that masturbation is a definite cause of insanity in women in a single case.[325] Koch also reaches a similar conclusion, as regards both sexes, though he admits that masturbation may cause some degree of psychopathic deterioration. Even in this respect, however, he points out that "when practiced in moderation it is not injurious in the certain and exceptionless way in which it is believed to be in many circles. It is the people whose nervous systems are already injured who masturbate most easily and practice it more immoderately than others"; the chief source of its evil is self-reproach and the struggle with the impulse.[326]