As the nation heads into the last 10 days of this election, plenty of things are still unknowable.

How big a role will race play in the outcome, and will we finally be able to admit the obvious, that an African-American candidate faces some hurdles that a white candidate does not?

Will that Associated Press poll of likely voters that put Sen. John McCain within spitting distance of Sen. Barack Obama, while almost all other polls show him trailing badly, turn out to have been a statistical anomaly or a harbinger of an upset?

Will Joe the Plumber be able to unclog the blocked drains of the McCain campaign, or will he be drowned out by Stan the Steelworker and Nancy the Nurse clamoring for a thorough White-House-cleaning in the face of an economic meltdown?

Who decided it was a good idea to position Alaska Gov. Sarah Palin as an average, everyday, lipstick-wearing hockey mom, and then get her a $150,000 hair and wardrobe make-over for the vice-presidential campaign (although they sure got their money's worth; the woman has been looking fabulous)?

What on earth was Sen. Joe Biden thinking when he rambled on and on with his "guarantee" that if Mr. Obama becomes president, foreign powers would manufacture a crisis to test him within the first six months (which would undoubtedly be true for any new president, but why bring it up in relation to the top of your own ticket)?

And how did New York, the only American city whose central business district was attacked by al-Qaida on Sept. 11, 2001 -- the city from which Saks Fifth Avenue, Ms. Palin's clothing source, derives its name; the city that still has a gaping hole in the skyline where the twin towers of the World Trade Center once stood -- wind up on the McCain/Palin list of "un-American" places?

The list could go on, but here's one thing, at least, that is no longer in question. The long, bruising Democratic primary race between Mr. Obama and Sen. Hillary Clinton did not weaken the party or hobble either one of them politically. In fact, it seems clear now that these two adversaries made each other better speakers, better campaigners and better standard-bearers for a post-Bush vision for the country.

You wouldn't have thought this possible from all the dire predictions that preceded, and even followed, Mrs. Clinton's concession speech in June. But at this point in the campaign, Mr. Obama is so far ahead of Mr. McCain in so many polls, it's hard to see him as damaged in any way by his protracted clash with Mrs. Clinton. On the contrary, the epic battle only served to toughen him up, stiffen his spine and sharpen his focus.

Granted, the collapse of the banking and mortgage industries changed the playing field almost overnight. That would have put any Republican at a disadvantage, since the GOP has been running Washington for the past eight years. But the meltdown was even worse for Mr. McCain. He looked completely flummoxed as he floundered around in search of a cogent response before hitting upon the fellow from Toledo (who turned out not to be a plumber after all, and whose taxes would not, in fact, go up under Mr. Obama's plan, but who still made for a useful symbol and a great sound bite).

In reacting to the crisis, Mr. Obama was able to put forth a response that strikes many voters, including those essential independents and even former GOP Secretary of State Colin Powell, as thoughtful, reasoned, calm and steady. He offered specifics (even if they're not all completely realistic or even doable given the nation's debt crisis) and he skipped the high-flying rhetoric that left a lot of Democrats cold during the primary. One reason he was ready to pull this off is because of the lessons he learned going toe-to-toe with Mrs. Clinton.

That primary race also taught him some humility that wasn't always apparent in his early stump speeches. For all his victories in other parts of the country, Mrs. Clinton still cleaned his clock by nearly 10 points in Pennsylvania. And last week, after most polls gave him a third debate victory against Mr. McCain, he said this to supporters:

"For those of you who are feeling giddy or cocky and think this is all set, I just [have] two words for you: New Hampshire. You know I've been in these positions before where we were favored and the press starts getting carried away and we end up getting spanked. And so that's another good lesson that Hillary Clinton taught me."

Cynics might say that comment was designed not only to pry more money out of the crowd but also to win over Hillary hold-outs who are still angry about this young upstart stealing the nomination that they believe should have been hers. Whatever the motivation, it was a smart thing to say, and a true one.

Mrs. Clinton, for her part, has been an effective and enthusiastic campaigner for Mr. Obama. If she had been this clear and convincing from the beginning of her own campaign, she might have won the nomination.

Perhaps her finest moment came at the Democratic Convention, when she urged her supporters to back her former opponent because he was the only one who could deliver on the things that mattered to her and to them:

"I want you to ask yourselves: Were you in this campaign just for me? Or were you in it for that young Marine and others like him? Were you in it for that mom struggling with cancer while raising her kids? Were you in it for that boy and his mom surviving on the minimum wage? Were you in it for all the people in this country who feel invisible?"

At that moment, a lot of Democrats might have wondered if they'd picked the right horse. Two months later, that question isn't much in doubt.