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.The quote is attributed to Dr. Martin Luther King, Jr.
As it turns out, it's not all MLK. Everything but the first sentence comes from King's 1963 book, Strength to Love.
The first sentence actually started out as a comment presented with the remaining quote in someone's Facebook status update. For some reason, people who copied and pasted this person's status moved the opening quotation mark to include the comment. Here's the original (click image to view larger version):
The extra sentence is a great sentiment, and one with which I am sure MLK would agree. ("Fake but accurate", as newsman Dan Rather said in another context.)
Due to the tireless efforts of well-meaning people, future generations will swear up and down that MLK actually said it.
(Via: St Eutychus)