What is an insight about life pertaining to justice in The Crucible?

Sometimes, we can't rely on external sources to provide
justice for us. In The Crucible, relying on the courts for true
justice did not work out too well for many people in Salem.  In act three, as John,
Francis, Giles and Mary come to the courts with firm proof and logical rationale
regarding the cases in the court at the time, the judges refused to dispense equal and
fair justice.  Innocent people were hanged, and many others unfairly jailed.  The courts
were supposed to enact justice and did not.  The message was clear:  do not rely on the
courts for justice.

Also, do not rely on others to be
just.  If everyone in the play had been just, no accusations would have been made.  In
fact, many of the accusations made were people's attempts to thwart justice's own
demands of them.  Justice would demand that Abby and the girls be punished for dancing
and casting spells; to avoid that justice, they lied and accused others.  If anyone in
Salem counted on people being kind, fair, and just, they were disappointed.  Instead,
fear, paranoia, panic, betrayal, jealousy and greed reigned
supreme.

The only true justice that occurs in the play is
the justice that people are able to bring to their own hearts.  At the end of the play,
John finally is at peace with himself.  He feels like he has finally paid for his sins,
and done enough good deeds to earn redemption.  He walks to the gallows a free man,
because he brought his own justice to his life.  He paid for his sins, he righted his
wrongs.  He was justified and at peace at the end.

The
major message is to not rely on others, or institutions for justice; it will often end
in disappointment and wrongdoing. Instead, find your own way.  I hope that helped; good
luck!