Within each of us lies conflicting forces: yin and yang, light and dark, good and evil.
— Uncle, Jackie Chan Adventures
Dr. Jimmy and Mr. Jim, when I'm pilled you don't notice him. He only comes out when I drink my gin!
— Dr. Jimmy, Quadrophenia
We have here an unusual opportunity to appraise the human mind, or to examine, in Earth terms, the roles of good and evil in a man. His negative side, which you call hostility, lust, violence, and his positive side, which Earth people express as compassion, love, tenderness.
— Mr. Spock, Star Trek: The Original Series, "The Enemy Within"