Martin Luther King, Jr. on progress

"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