In retrospect, we often recall political debates in terms of decisive moments, like George H. W. Bush looking at his watch impatiently in the town meeting-style debate with Bill Clinton and H. Ross Perot in 1992. That, of course, was the past debate that most resembled last night's. Even though John McCain knew it and tried to avoid Bush 41's seeming diffidence to economic pain by standing as close to his questioners as the debate rules and social custom permit, he was nonetheless, like Bush, the bystander to another candidate's learned mastery of the emotional touchstones of economic politics.

But the moment we remember is often just a mnemonic for the overall effect of a debate. That "is this over yet?" glance at the watch in 1992 said it all about a debate between a young man who had some kind of appreciation for economic circumstances, and an older man so steeped in conservative banalities that he had nothing. And whether it is John McCain's disdainful reference to his rival as "that one" that is remembered, or some other snapshot, the overall effect was much like the Bush-Clinton-Perot debate -- as close to a complete trouncing as real-world politics offers.

The 90 minutes of debate has to be seen in the context of the preceding days. The week began with the McCain campaign's announcement that now the gloves were really, really coming off. Then Sarah Palin, Fox News, and, to a somewhat lesser extent, McCain himself descended into firing up the base by encouraging their loyalists to believe that Obama was a pal-of-terrorists and perhaps a traitor.

McCain's crazed negativity may not have been the nastiest in recent history -- it's always hard to maintain perspective, or even remember exactly what happened, four or 20 years ago. But it surely violated three basic rules of campaigning devised by Lee Atwater and Karl Rove for Bush per et fils:

1. Keep your name and face off the most vicious attacks. The Bushes maintained credible distance and deniability about the Willie Horton attacks against Dukakis and the Swift Boat attacks on John Kerry. But McCain's name is all over the attack ads on Obama, like the one claiming that he supported sex education for kindergartners. That deadly disclaimer "I'm John McCain and I approve this message" was of course added by virtue of the campaign-finance law that is McCain's one notable accomplishment.

2. Establish your positive message before going hard-negative. Is there a McCain governing message? On foreign policy, it's war. On the economy, who knows?

3. Attacks don't have to be true, or even have a grain of truth, but they have to resonate with something people already associate with the target, and have enough proximity to the truth that the media will echo them, at least as a possibility. McCain's ads calling Obama a vacuous celebrity met that low bar; "palling around with terrorists" doesn't.

To these, I would add a fourth -- you have to have the nerve to stick with it. McCain built up the expectation that he would deliver the fatal blow at last night's debate. And yet, given the opportunity to put an exclamation point on all the ads and surrogate speeches, he backed down. The seething anger was still present, but it was as empty and inexplicable as his policy proposals.

The big news of the week came in Mike Allen's article arguing McCain was "grumpy" and "miserable about having to run a campaign that's antithetical to his persona," and John Heilemann's examination in New York Magazine of how McCain lost his brand. The latter article explains, in part, why the campaign made the three mistakes it did: It "expected the McCain brand ... to be everlasting." Since 2001, Heilemann says, "it had proved durable, most of all with the press, which consistently saw McCain's deviations from what were supposed to be his core beliefs as aberrations." Believing that McCain's honorable, straight-talker, partisan-mediator image was unshakable, his campaign thought it could get away with anything.

Now, as one who has seen the McCain "brand" as a bit of a scam for many years, I see this reckoning as long overdue. But reading Heilemann, I started to feel a bit of sympathy for McCain. Sure, he used the press. Sure, he exploited the scarce opportunities for bipartisanship in the Bush-era Congresses to monopolize them, rarely for good. But he was also used by the press. They needed him -- for good quotes, for windows into an otherwise closed legislative process -- to shake things up occasionally and create some drama. He was used by Democrats, who had no other way to build any kind of majority. He was used by the nonpartisan grandees of the foundation and nonprofit world, who lavished glory on McCain because it made them feel respectable and bipartisan.

But today, he serves none of those purposes. The image he created for himself collapsed in part because he shattered it with his campaign's insane, short-term tactical posturing. But its foundations had fallen out long before that. What McCain didn't realize is that the brand he had constructed had less to do with him than with the political moment in which it was useful. That moment is now over.