“Violence as a way of achieving racial justice is both impractical and immoral. It is impractical because it is a descending spiral ending in destruction for all. The old law of an eye for an eye leaves everybody blind. It is immoral because it seeks to humiliate the opponent rather than win his understanding; it seeks to annihilate rather than to convert. Violence is immoral because it thrives on hatred rather than love. It destroys community and makes brotherhood impossible. It leaves society in monologue rather than dialogue. Violence ends by defeating itself. It creates bitterness in the survivors and brutality in the destroyers.”

1950s, Three Ways of Meeting Oppression (1958)
Context: Violence as a way of achieving racial justice is both impractical and immoral. It is impractical because it is a descending spiral ending in destruction for all. The old law of an eye for an eye leaves everybody blind. It is immoral because it seeks to humiliate the opponent rather than win his understanding; it seeks to annihilate rather than to convert. Violence is immoral because it thrives on hatred rather than love. It destroys community and makes brotherhood impossible. It leaves society in monologue rather than dialogue. Violence ends by defeating itself. It creates bitterness in the survivors and brutality in the destroyers.

1960s, Keep Moving From This Mountain (1965)

"An eye for an eye leaves everybody blind" is of indefinite origin, but has been disputably attributed to various figures, including Mahatma Gandhi. This variant describing it as an "old law" is attributed to King in The Words of Martin Luther King, Jr., (2008) http://books.google.com/books?id=irMxJS36904C&redir_esc=y by Coretta Scott King, Second Edition ; it also occurs in the credits of Spike Lee's movie Do the Right Thing (1989).
Disputed

Venom and Eternity (1951), Danielle's Monologue

Source: The Revolt of the Masses (1929), Chapter XV: We Arrive At The Real Question

"Building a Moral Society", Chamberlin Lecture at Lewis & Clark College (1995)
Context: An immoral society betrays humanity because it betrays the basis for humanity, which is memory. An immoral society deals with memory as some politicians deal with politics. A moral society is committed to memory: I believe in memory. The Greek word alethia means Truth, Things that cannot be forgotten. I believe in those things that cannot be forgotten and because of that so much in my work deals with memory... What do all my books have in common? A commitment to memory.

Ideal Family and Ideal World http://www.unification.net/1982/820606.html (1982-06-06)

Source: The Rose of Paracelsus (2015), p. 187