Founded on the sense of vision also we find a phenomenon, bordering on the abnormal, which is by Moll termed mixoscopy. This means the sexual pleasure derived from the spectacle of other persons engaged in natural or perverse sexual actions. (Moll, _Konträre Sexualempfindung_, third edition, p. 308. Moll considers that in some cases mixoscopy is related to masochism. There is, however, no necessary connection between the two phenomena.) Brothels are prepared to accommodate visitors who merely desire to look on, and for their convenience carefully contrived peepholes are provided; such visitors are in Paris termed "_voyeurs_." It is said by Coffignon that persons hide at night in the bushes in the Champs Elysées in the hope of witnessing such scenes between servant girls and their lovers. In England during a country walk I have come across an elderly man carefully ensconced behind a bush and intently watching through his field-glass a couple of lovers reclining on a bank, though the actions of the latter were not apparently marked by any excess of indecorum. Such impulses are only slightly abnormal, whatever may be said of them from the point of view of good taste. They are not very far removed from the legitimate curiosity of the young woman who, believing herself unobserved, turns her glass on to a group of young men bathing naked. They only become truly perverse when the gratification thus derived is sought in preference to natural sexual gratification. They are also not normal when they involve, for instance, a man desiring to witness his wife in the act of coitus with another man. I have been told of the case of a scientific man who encouraged his wife to promote the advances of a young friend of his own, in his own drawing-room, he himself remaining present and apparently taking no notice; the younger man was astonished, but accepted the situation. In such a case, when the motives that led up to the episode are obscure, we must not too hastily assume that masochism or even mixoscopy is involved. For information on some of the points mentioned above see, e.g., I. Bloch, _Beiträge zur Ætiologie der Psychopathia Sexualis_, Teil I, pp. 200 _et seq._; Teil II, pp. 195 et seq.