Eulenburg, Sexuale Neuropathie, p. 114.
 Bernaldo de Quiros and Llanos Aguilaniedo (La Mala Vida en Madrid, p. 294) knew the case of a man who found pleasure in lying back on an inclined couch while a prostitute behind him pulled at a slipknot until he was nearly suffocated; it was the only way in which he could attain sexual gratification.
 Arrest of respiration, it may be noted, may accompany strong sexual excitement, as it may some other emotional states; one recalls passages in the Arabian Nights in which we are told of ladies who at the sight of a very beautiful youth “felt their reason leave them, yearned to embrace the marvelous youth, and ceased breathing.” Inhibited respiration is indeed, as Stevens shows ("Study of Attention,” American Journal of Psychology, Oct., 1905), a characteristic of all active attention.
 The exact part played by the respiration and even the circulation in constituting emotional states is still not clear, although various experiments have been made; see, e.g., Angell and Thompson, “A Study of the Relations between Certain Organic Processes and Consciousness,” Psychological Review, January, 1899. A summary statement of the relations of the respiration and circulation to emotional states will be found in Kuelpe’s Outlines of Psychology, part i, section 2, § 37.
 The words alluded to by my correspondent are as follows: “I needed a struggle; what I needed was that feeling should guide life, and not that life should guide feeling. I wanted to go with him to the edge of an abyss and say: ’Here a step and I will throw myself over; and here a motion and I have gone to destruction’; and for him, turning pale, to seize me in his strong arms, hold me back over it till my heart grew cold within me, and then carry me away wherever he pleased.” The whole of the passage in which these lines occur is of considerable psychological interest. In one English translation the story is entitled Family Happiness.
Pain, and Not Cruelty, the Essential Element in Sadism and Masochism—Pain Felt as Pleasure—Does the Sadist Identify Himself with the Feelings of his Victim?—The Sadist often a Masochist in Disguise—The Spectacle of Pain or Struggle as a Sexual Stimulant.
In the foregoing rapid survey of the great group of manifestations in which the sexual emotions come into intimate relationship with pain, it has become fairly clear that the ordinary division between “sadism” and “masochism,” convenient as these terms may be, has a very slight correspondence with facts. Sadism and masochism may be regarded as complementary emotional states; they cannot be regarded as opposed states. Even De Sade himself, we have seen, can scarcely be regarded as a pure sadist. A passage in one of his works expressing regret that sadistic