What are some specific instances, in chronological order, of how John Proctor's character becomes dynamic?

1. In Act Three, John Proctor becomes willing to tarnish his reputation to save his wife, something he'd been unwilling to acknowledge as a potential necessity in Act Two.  It seems as though he is finally able to recognize how diabolical and capable of evil Abigail Williams is, and he comes to the court with Mary Warren to make her tell the truth about how the girls are lying to the court.  He finally admits to Deputy Governor Danforth what he was unwilling to tell Mr. Hale: that he is a lecher, that he has "known" Abigail sexually, and that this is the reason she is accusing his wife.
2. In Act Four, John finally learns to recognize his own goodness.  Prior to now, it seems that he'd only been able to focus on his sin of adultery, and he felt that he was bad, a terribly sinful man.  However, in the play's final pages, John decides not to confess a lie to save his life, but, rather, to tear up his confession and refuse to give in to the corrupt court (an act that would cast doubt on the innocence of those other innocent people with whom he is scheduled to be hanged).  He tells Danforth,

You have made your magic now, for now I do think I see some shred of goodness in John Proctor.  Not enough to weave a banner with, but white enough to keep it from such dogs.

This new sense of his own goodness as a person proves how much John has changed.