OXFORD, Miss.

The first debate seemed like the perfect moment for Barack Obama to re-enact the Code Red courtroom scene from “A Few Good Men,” to slide under John McCain’s skin and irritate until he goaded McCain into doing exactly what he really wanted to do: tell off the whippersnapper who’d never bled for his country.

It would have been easy for smarty-pants Obama to get in the face of the temperamental older guy, just as Tom Cruise did with Jack Nicholson, to push him into erupting into some version of that climactic speech, like, “Deep down, in places you don’t talk about at your fancy faculty club, you want me on that wall, you need me on that wall.”

The timing was ideal. McCain was so aggressively erratic as he did his free-form break dance around the economy last week that it seemed the only possible explanation was that he was creating a wild diversion to distract people from Sarah Palin’s stunningly junior varsity appearance with Katie Couric.

Once Garbo began to speak, and people realized that Palin had a few key lacunae in her understanding of the globe and even of her running mate’s record, the myth of the Alaska superwoman continued to unravel.