Michael Phelps has left us only with questions of history.
He is master of his present. No one can argue otherwise now that he has won eight gold medals and swum better than any other human ever has at the Beijing Olympics. Competitors rarely bother to call him the best anymore because, well, duh!
It is folly to frame the thing in those terms. After all, was Abraham Lincoln a greater leader than Queen ElizabethI? Is Yo-Yo Ma a more profound musician than Jimi Hendrix?
Adherents might claim one or the other with some ferocity, but most rational people know these questions are unanswerable. Yet we ask them. What else to do when a fellow human leaves us in bewildered awe?
Phelps has at least put himself in a class of athletes unassailably the best at their respective arts. Tiger Woods, Michael Jordan, Steffi Graf, Roger Federer and others have apartments in this pantheon. But when deciding which performer deserves the penthouse, how do you set the terms?
"He's right there in the top echelon," said National Public Radio commentator Frank Deford, who has seen his share of great ones in almost 50 years as a sportswriter.
"It's always difficult to compare him with people in team sports because it's easier to stand out in an individual sport. But I don't know that there's ever been anything like this. It's extraordinary."
Phelps' masterpiece has seemed more condensed and thus more intense to Deford than the great moments of Woods or Federer or Jordan.
"I don't know if anybody's ever owned a week like this," he said.
Phelps might be the most remarkable Olympian in memory, said Bob Dorfman, who studies the marketing potential of Olympic athletes for San Francisco-based Baker Street Partners.
"Maybe he doesn't bring the drama of Kerri Strug vaulting on a broken ankle, but in terms of sheer athletic performance, he's just jaw-dropping," Dorfman said.
"He's doing something that no one else has done, which puts him in that Tiger Woods category. His performance is really hard to top."
Just don't ask Phelps to sort all this out, at least not yet.
"I literally just get in the water and swim," he said when asked to weigh himself against other great Olympians.
"That's all I think about."
But his coach, Bob Bowman, isn't afraid to proclaim his student as the best.
"I think if it was over today, he's the greatest Olympian who ever lived," Bowman said in Beijing late last week.
"I do think it's difficult to compare [the different sports], but in terms of just sheer dominance in his events and the times he's putting up and what he's doing now in two Olympics - really three, but two where we won medals - I think it's hard to argue."