Dr. Faustus and Power

I can definitely see the decline in power that Hannah was talking about. I think it is interesting to talk about what causes this deterioration, I would argue that it is to show the lack of power humans ever really have. It reveals the utter depravity of mankind. In his arrogance, Faustus assumed that with power, he would achieve great things.  At the beginning he asks himself why he couldn't be eternized(line 18).  This is an example of how highly he esteems himself. He views himself to be so great that it is reasonable for the world to know his name. 
 Yet as the play continues the true ugliness of his character is revealed.  Like Hannah mentioned, he uses the power he has for practical jokes. And worse than that, Mephastophilis is able to lock in his soul by parading a pretty girl in front of him.  Ultimately, I think Faustus never really had that much power. The power he was given revealed the ultimate ugliness of his soul.