I think that Proctor's power changes over the play as his voice becomes more definite. I don't think that it is accident that Proctor's wish to become invisible and not be involved involves him not having power. In the first one and a half Acts, this is evident. Proctor is frustrated at not being heard both in public with others and with his own wife at home. It is only towards the end of the Second Act where Proctor's power begins to assert itself because Proctor begins to use his voice in defining his own world. When he says to Mary that his wife will not go to jail because of Abigail and he will do what he needs to free his wife, it is a moment where Proctor starts to show power because he activates his voice. When Proctor steadies Corey and the trial and shows support to Nurse, it is a moment when Proctor uses his voice and demonstrates his power. Even when he confesses to adultery in the trial, he does so to show power and in the process his voice or his "name" becomes something more evident. Certainly, by the end of the drama, Proctor might lack political power, but he represents a domain whereby power and autonomy are transcendent, something that even he knows might go beyond the temporal condition of Salem and represent what it means to possess power and voice, in a more universal sense.