The preacher in him would have continued speaking out against injustice, war and maybe even pop culture. He would likely not have run for president. He probably would have endured more harassment from J. Edgar Hoover.

Four decades after the Rev. Martin Luther King Jr. fell to an assassin's bullet, colleagues and biographers offer many answers to the question: What if he had lived?

For his children, however, the speculation is more personal. They know their lives would have turned out differently had they had their beloved father to guide and teach them.

Instead, history moves on, remaking the world in myriad ways. The nation has grappled with issues of race and inequity without the benefit of King's evolving wisdom. A generation has come of age celebrating him in a national holiday, like other figures of the frozen past.