"I mourn the loss of thousands of precious lives, but I will not rejoice in the death of one, not even an enemy." "Returning hate for hate multiplies hate, adding deeper darkness to a night already devoid of stars. Darkness cannot drive out darkness: only light can do that. Hate cannot drive out hate: only love can do that." ~ Martin Luther King, Jr.
update: turns out that the 1st part of this quote wasn't by MLK, Jr. So I've bolded the part that was his actual quote. Instead of deleting the part that he didn't say, I left it in because I still think it's poignant.