Forty years ago yesterday evening, the Rev. Dr. Martin Luther King Jr. preached his last sermon, at the Mason Temple, the World Headquarters of the Church of God in Christ in Memphis.

Dr. King had been in a reflective, but somber, mood as he scanned the audience from the dais that evening. He was tired all the way down to his spirit.

Mopping his forehead, he spoke of hopes and premonitions. The sound of rain and distant thunder overhead complemented his mood as the ladies fanned themselves and the men prepared to shout "amen."

He began his last sermon with a fanciful notion that was both grandiloquent and tragically prophetic. He asked his listeners to imagine God making him an offer he couldn't refuse:

"If I were standing at the beginning of time, with the possibility of general and panoramic view of the whole human history up to now," he said, "and the Almighty said to me, 'Martin Luther King, which age would you like to live in?' -- I would take my mental flight by Egypt through, or rather across the Red Sea, through the wilderness on toward the Promised Land. And in spite of its magnificence, I wouldn't stop there."

He listed other times and places he considered during his panoramic flight through history: Greece during the era of the classical philosophers. The heydays of the Roman Empire, the Renaissance and the Reformation. Abraham Lincoln issuing the Emancipation Proclamation in 1863. Franklin Roosevelt ushering in the New Deal in the 1930s.

"But I wouldn't stop there," he said. "I would turn to the Almighty and say, 'If you allow me to live just a few years in the second half of the 20th century, I will be happy.' "

Dr. King insisted that he enjoyed living at the midpoint of the 20th century because he could see God working in history and changing the order of things for the better, despite the prevalence of injustice around the world.

He acknowledged the nation's sickness and its unwillingness to grapple with the legacy of its racist past.

But even with the specter of death breathing down his neck, he found himself admiring how far black folks had come since the Montgomery bus boycotts the previous decade.

"I can remember when Negroes were just going around as Ralph [Abernathy] has said, scratching where they didn't itch, and laughing when they were not tickled. But that day is all over. We mean business now, and we are determined to gain our rightful place in God's world."

Despite its downbeat tone, it was essentially an optimistic sermon that looked expectantly to the birth of an America that was less prejudiced than it was on that spring day during a very tumultuous year.

After recalling a Harlem book signing in the 1950s when a disturbed black woman stabbed him in the chest, he said how grateful he was to be alive.

He'd lived long enough to see the lunch counter sit-ins of the early 1960s, he told them. He'd seen the protests in Birmingham. He'd lived long enough to deliver his "I Have a Dream" speech in 1963. He witnessed the signing of two major civil rights bills by President Lyndon Johnson. America was moving forward, albeit reluctantly.

"And then I got to Memphis," he said, winding down his sermon. The Rev. King looked like a man who was awash in a sea of death.

"Well, I don't know what will happen now," he said with the sober fatalism of a man who was regularly reminded of his mortality by threatening phone calls in the middle of the night. "We've got some difficult days ahead."

His flight to Memphis had been delayed by a bomb threat, so there was an edge to his preaching that night.

"But it doesn't matter with me now. Because I've been to the mountaintop and I don't mind," he said, giving thanks to God for letting him live through such interesting times.

"And He's allowed me to go up to the mountain. And I've looked over. And I've seen the Promised Land. I may not get there with you," he said, "but I want you to know tonight, that we, as a people, will get to the Promised Land."

What did Martin Luther King Jr. see when he glimpsed the outline of the Promised Land from his vantage point in 1968? Would he have been just as amazed as we are by an election cycle that promises to upend American history?

Documentarian Daniel Love began his award-winning film "Charles Moore: I Fight With My Camera" while he was a senior at Allderdice High School in 2002.

Mr. Moore was, arguably, the pre-eminent photographer of the Civil Rights movement. His images captured the drama of that era like none other. Mr. Love's documentary will be shown on WQED on Monday at 10:30 p.m. It is one of the best documentaries ever produced about the protests against American apartheid.