The X Files1993

Mulder:
When I first came to work with the FBI I worked in violent crimes. I saw the worst of humanity; I saw monsters, and I wondered how they became that way - how these men became so evil. And there are psychological explanations: victims of their environment, victims of their parents, but the scientific explanations were never truly satisfied. And I began to think about evil like a disease, how it goes from man to man or age to age. Most of us walk around thinking that we're incapable of any acts of evil, and we are. We can stifle that momentary urge to kill or to hurt, we have some kind of immunity to it. But I think it's possible that there's an occurrence in somebody's life, a tragedy or a loss, that leaves them vulnerable; hurts their immunity to evil. And all of a sudden, at that point in their lives when they're weakened, they're open to evil... and they can become evil.