The movie perfectly represents the dream's theories, levels of reality and psychological creativity of a person. Cobb hires an architect to create a dream scenario for his target so that he can devise an idea in his target's mind. They make a team and build up a plan to go into target's dream's dream to devise an idea that can bring profit to Saito. But, as cobb is so professional in INCEPTION, every person of his team has a totem which tells them whether they are in dream world or in real world. 

There comes a scene where Cobb asks Ariana to make a totem for herself and don't reveal its secret to anyone else. Then the question comes here, Why he tells her, his own totem's secret??