In One Flew Over the Cuckoo's Nest, the main conflict is often seen as the struggle between the individual and the oppressive system known as the Combine, or, as some critics describe it, the clash between Nature and the Machine. However, there is also a notable secondary conflict between male and female characters. Kesey portrays the hospital as a matriarchal society, with Big Nurse holding the power, which she receives from a female supervisor. Nurse Ratched emasculates the men, including the timid Dr. Spivey, and infantilizes the male patients through her maternal approach. McMurphy describes her as "a ball-cutter." Other women who exert similar control include Chief Bromden's mother, Billy Bibbit's mother, and Dale Harding's wife. To help the men regain their self-esteem, McMurphy—driven by his insatiable animalistic desires—focuses on restoring their sexual confidence. He does this by telling stories of young virgins that excite the Chief and by arranging for Billy to have an encounter with the prostitute, Candy. McMurphy also challenges Nurse Ratched's authority sexually, from flaunting himself in whale-patterned underwear to symbolically invading her glass office, culminating in a climactic scene where he exposes her breasts. Some critics have criticized the novel for its sexual stereotypes, particularly Kesey's portrayal of women as oppressive forces. However, others, including Kesey, argue that One Flew Over the Cuckoo's Nest promotes the free expression of sexual energy for both men and women and critiques not women themselves but a lack of warmth and compassion.