King Jr.

Nonviolence means avoiding not only external physical violence but also internal violence of spirit. You not only refuse to shoot a man, but you refuse to hate him.
~ Martin Luther King, Jr.

The ultimate weakness of violence is that it is a descending spiral, begetting the very thing it seeks to destroy. Instead of diminishing evil, it multiplies it. Through violence you may murder the liar, but you cannot murder the lie, nor establish the truth. Through violence you may murder the hater, but you do not murder hate. In fact, violence merely increases hate. 

So it goes. 

Returning violence for violence multiplies violence, 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.

~ Martin Luther King, Jr.

On some positions, Cowardice asks the question, “Is it safe?” Expediency asks the question, “Is it politic?” And Vanity comes along and asks the question, “Is it popular?” But Conscience asks the question “Is it right?” And there comes a time when one must take a position that is neither safe, nor politic, nor popular, but he must do it because Conscience tells him it is right.

~ Martin Luther King, Jr.