A famous line from Martin Luther King, Jr. comes to mind: "Darkness cannot drive out darkness, only light can do that. Hatred cannot drive out hatred, only love can do that."
In Hamlet we see the negative side of this aphorism as Hamlet attempts to drive out darkness with yet more darkness, violence with more violence.
Several wise sayings come from Hamlet itself. I am personally fond of "Neither a borrower or a lender be," which strangely comes from Polonius, hardly noted for his wisdom in the play. But it is advice he gives his son Laertes as he departs.
yeah for me to the best one was like coryengle...."better late than never.."
"Better late than never."