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.
-- Dr. Martin Luther King Jr. (15 January 1929 - 4 April 1968), Baptist minister, civil rights activist, and Nobel laureate, Strength to Love (1963), Chapter 1