On this Martin Luther King Day, a number of information services offer samplings of King's thoughts.
My friends at http://www.602communications.com provided this nugget this morning, as found in WikiQuote. It's from King's Strength to Love (1963).
"The tough mind is sharp and penetrating, breaking through the crust of legends and myths and sifting the true from the false. The tough-minded individual is astute and discerning. He has a strong austere quality that makes for firmness of purpose and solidness of commitment. Who doubts that this toughness is one of man's greatest needs? Rarely do we find men who willingly engage in hard, solid thinking. There is an almost universal quest for easy answers and half-baked solutions. Nothing pains some people more than having to think.
"Softmindedness often invades religion. ... Softminded persons have revised the Beatitudes to read "Blessed are the pure in ignorance: for they shall see God." This has led to a widespread belief that there is a conflict between science and religion. But this is not true. There may be a conflict between softminded religionists and toughminded scientists, but not between science and religion. ... Science investigates; religion interprets. Science gives man knowledge which is power; religion gives man wisdom which is control. Science deals mainly with facts; religion deals mainly with values. The two are not rivals. They are complementary.
"There is little hope for us until we become toughminded enough to break loose from the shackles of prejudice, half-truths, and downright ignorance. The shape of the world today does not permit us the luxury of softmindedness. A nation or civilization that continues to produce softminded men purchases its own spiritual death on the installment plan. But we must not stop with the cultivation of a tough mind. The gospel also demands a tender heart. ... What is more tragic than to see a person who has risen to the disciplined heights of toughmindedness but has at the same time sunk to the passionless depths of hardheartedness?
"Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity. 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. So when Jesus says "Love your enemies," he is setting forth a profound and ultimately inescapable admonition. ... 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.
"The ultimate measure of a man is not where he stands in moments of comfort and convenience, but where he stands at times of challenge and controversy."