80. Memento (2001)
Leonard, an amnesiac, wakes up every morning having to learn the basic focus of his life: his wife was killed and the man responsible is still at large. Leonard must track down the man and kill him, for her sake. As the morning wears on, he discovers the notes, tattoos and clues he has left himself to discover the attacker.
As a unit, the human race is powerful, able to change the surface of the earth. As an individual, a human being is weak. Yes, a single human being can be amazingly creative or destructive. single human can change the flow of history, potentially. But any plans a human can make can be disrupted by another person. Each person is limited by their weakness. And if another knows a person’s weakness, in detail, they can manipulate them to their own devises. If a person’s weakness is lust, those who have the ability to sate that lust have complete power over them. If a person’s weakness is fear, those who manipulate fear successfully have complete control over them.
And if Leonard's weakness is obsession, the one who feeds that obsession knowingly has complete control over him. It is not the obsession that controls him, but the one who knows how to use the obsession to make him do as they please.
To understand and use a person’s weakness is the ability to control them.