Martin Luther King, Jr., Strength To Love, 1963

Darkness cannot drive out darkness; only light can do that.

Hate cannot drive out hate; only love can do that.

Hate multiplies hate, violence multiplies violence,
and toughness multiplies toughness in a descending spiral of destruction

... The chain reaction of evil -- hate begetting hate, wars producing more wars
-- must be broken,
or we shall be plunged into the dark abyss of annihilation.

Martin Luther King, Jr.
Strength To Love, 1963.