The sadist attempts to destroy the ego in an effort to unify the id and super-ego, in effect gratifying the most base desires the sadist can express while ignoring or completely suppressing the will of the ego, or of the conscience. Thus, Deleuze attempts to argue that masochism and sadism arise from such different impulses that the combination of the two terms is meaningless and misleading. A masochists perception of their own self-subjugating sadistic desires and capacities are treated by Deleuze as reactions to prior experience of sadistic objectification. (For example, in terms of psychology, compulsively defensive appeasement of pathological guilt feelings as opposed to the volition of a strong free will.) The epilogue of Venus In Furs shows the character of Severin has become embittered by his experiment in the alleged control of masochism, and advocates instead the domination of women.Before Deleuze, however, Sartre had presented his own theory of sadism and masochism, at which Deleuzes deconstructive argument, which took away the symmetry of the two roles, was probably directed. Because the pleasure or power in looking at the victim figures prominently in sadism and masochism, Sartre was able to link these phenomena to his famous philosophy of the "Look of the Other". Sartre argued that masochism is an attempt by the "For-itself" (consciousness) to reduce itself to nothing, becoming an object that is drowned out by the "abyss of the Others subjectivity".
It is poorly understood, though, what ultimately connects these emotional experiences to sexual gratification, or how that connection initially forms. Dr. Joseph Merlino, author and psychiatry adviser to the New York Daily News, said in an interview that a sadomasochistic relationship, as long as it is consensual, is not a psychological problem:

Its a problem only if it is getting that individual into difficulties, if he or she is not happy with it, or its causing problems in their personal or professional lives. If its not, Im not seeing that as a problem. But assuming that it did, what I would wonder about is what is his or her biology that would cause a tendency toward a problem, and dynamically, what were the experiences this individual had that led him or her toward one of the ends of the spectrum. It is usually agreed on by psychologists that experiences during early sexual development can have a profound effect on the character of sexuality later in life. Sadomasochistic desires, however, seem to form at a variety of ages. Some individuals report having had them before puberty, while others do not discover them until well into adulthood. According to one study, the majority of male sadomasochists (53%) developed their interest before the age of 15, while the majority of females (78%) developed their interest afterwards (Breslow, Evans, and Langley 1985). The prevalence of sadomasochism within the general population is unknown.