What's It About?

I hope by now you have all realized how incorrectly the movie follows the plot of the book. The world Dumas describes in The Count of Monte Cristo is so extremely different from the one portrayed in film.
So, what is the novel about? What is Dumas trying to get at? What is his purpose in writing?
There are several answers to these questions, and each one of them correct in their scope. For me, the overriding theme was vengeance and justice. What is the difference between these two? Is there a difference? Is one right and the other wrong? And, if this is the case, how does one become socially acceptable over the other?
The concept around vengeance is to enact a reprisal against one who has done wrong to you. Justice, on the other hand, seems to follow a specific line of ensuring the retribution from one who has done wrong. Truly, the difference seems to lie in the hands of whom is enacting the punishment. For vengeance, it is the individual who has been wronged whereas justice is through a society determined process.
Within this definition, it appears that Edmond is strictly performing out of vengeance. But, is he? Can a person be enacting justice without filing formal complaints and leaving it in the hands of the "justice" system? Is there a higher power that determines this ability? To whom is Edmond accountable?