This pathological fetichism is connected, through gradual transitions, with physiological fetichism; so that (at least in body-fetichism) it is almost impossible to sharply define the beginning of the perversion. Moreover, the whole field of body-fetichism does not really extend beyond the limits of things which normally stimulate the sexual instinct. Here the abnormality consists only in the fact that the whole sexual interest is concentrated on the impression made by a part of the person of the opposite sex, so that all other impressions fade and become more or less indifferent. Therefore, the body-fetichist is not to be regarded as a _monstrum per excessum_, like the sadist or masochist, but rather as a _monstrum per defectum_. What stimulates him is not abnormal, but rather what does not affect him,—the limitation of sexual interest that has taken place in him. Of course, this limited sexual interest, within its narrower limits, is usually expressed with a correspondingly greater and abnormal intensity. It would seem reasonable to assume, as the distinguishing mark of pathological fetichism, the necessity for the presence of the fetich as a _conditio sine qua non_ for the possibility of performance of coitus. But when the facts are more carefully studied, it is seen that this limitation is really only indefinite. There are numerous cases in which, even in the absence of the fetich, coitus is possible, but it is incomplete and forced (often with the help of fancies relating to the fetich), and particularly unsatisfying and exhausting; and, too, closer study of the distinctive subjective psychical conditions in these cases shows that there are transitional states, passing, on the one hand, to mere physiological preferences, and, on the other, to psychical impotence in the absence of the fetich. It is therefore better, perhaps, to seek the pathological criterion of body-fetichism in purely subjective psychical states. The concentration of the sexual interest on a certain portion of the body that has no direct relation to sex (as have the mammæ and external genitals)—a peculiarity to be emphasized—often leads body-fetichists to such a condition that they do not regard coitus as the real means of sexual gratification, but rather some form of manipulation of that portion of the body that is effectual as a fetich. This perverse instinct of body-fetichists may be taken as the pathological criterion, no matter whether actual coitus is also possible or not.