Today is the birthday of Martin Luther King Jr. He would have been only 49.

Most of those we admire in American life and history had hardly finished their work at 49, but Dr. King's was finished when he kept his final date with destiny at the age of 39.

How could one man so touch and alter the American conscience in such a short life? How could such an ordinary man do so much?

And that is what Martin Luther King Jr. was: an ordinary man. Do you remember him as he was? Quiet spoken, of medium height and build, never a natural athlete or superachiever.

Do you remember his ordinary origins? A public-school student with parents who taught the principles of a conservative life. A man who, for most of his life, was noted neither for his social conscience nor perfection in his own life.

And don't forget the negative power of one other fact of his life: He was a black man in a white society.

But as he matured he found that the conditions of life were no barriers to the will or the mind, if you could discipline yourself. Martin Luther King Jr. learned the power of discipline many times and in many ways. He began disciplining his mind as a student at Morehouse College. His mastery of himself next led him to Boston University and to doctorate in systematic theology.

The open, disciplined mind he developed as a student was never allowed to deteriorate.

He was always hungry to know more. Up to the week of his death in Memphis 10 years ago, he read at least one book a week - not books of entertainment, but of substance.

I remember that one day during the bitter and terrifying days of the demonstrations in Selma, Ala., when I saw three books in his briefcase: one on Thoreau, one by the theologian-thinker Paul Tillich and a third on the life of Gandhi.

In those years of reading and thinking he had mastered the theory, art and practices of nonviolence that Gandhi's life exemplified.

But Dr. King never forget who he was, and so he delicately blended the ethnic, the ethical, the economic and the external to make his own formidable contribution to nonviolent change.

And though his life was consumed with practicing what he preached, he carefully taught all of us around him so that the work could go on regardless of what happened to the man.

Those he taught have carried on his widow, Coretta; Andrew Young, who went on to Congress and now holds Cabinet rank as ambassador to the United Nations; Walter Fauntroy, Washington's representative to Congress. There are many others.

Thousands have adopted the methods Dr. King perfected - especially those of confrontation politics, practiced today by such diverse interests as farmers, gays, browns and women.

But it was his principles that gave his methods their power. I heard him discuss the choice he had: to be political, which is to be expedient, or to be prophetic, which is to be morally motivated.

He never yielded on this. He remained a public-opinion molder and never became a public-opinion leader - that is, someone who reads the polls to find out where to lead.

And he did it, this ordinary man. He did it so well that his stature came to overshadow that of the Presidents of his day.

Yet every barrier he overcame led him to another, more formidable barrier. With each struggle, the odds became greater.

You and I know the damage that can be done when someone - a boss or a teacher - criticizes us, but imagine how it must have hurt Dr. King when a President of the United States and other civil-rights leaders said he was wrong to oppose the Vietnam war.

History, however, proved him right.

Martin Luther King Jr. won a Nobel Peace Prize and the admiration of many world leaders, yet all he really wanted was to continue to prove that the dreams of ordinary people are more powerful than any politics.