August 16, 1967, in Atlanta, Georgia. This is an excerpt of his talk, including the vocal responses from those in attendance. The full speech may be read at www.stanford.edu/group/King/publications
"And the other thing is, I'm concerned about a better world. I'm concerned about justice; I'm concerned about brotherhood; I'm concerned about truth. (That’s right) And when one is concerned about that, he can never advocate violence. For through violence you may murder a murderer, but you can't murder murder. (Yes) Through violence you may murder a liar, but you can't establish truth. (That's right) Through violence you may murder a hater, but you can't murder hate through violence. (All right, That’s right) Darkness cannot put out darkness; only light can do that." MLK Jr.