A quote from Martin Luther Kink Jr has been doing the rounds lately. The quote has been slightly mangled.
Here is the accurate quotation:
“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. Hate multiplies hate, violence multiplies violence, and toughness multiplies toughness in a descending spiral of destruction.”
See this link for more discussion of the quotation.