Life is short, but campaigns are long. And during the course of them, each candidate will have impressive and pathetic moments. But underlying the highs and lows, there are the fundamentals. The fundamentals of the Obama-Clinton race were on display Sunday morning.

Hillary Clinton went on "This Week With George Stephanopoulos" incarnating her role as the first Democratic Rambo. The Clinton campaign seems to want to reduce the entire race to one element: the supposed masculinity gap. Everything she does is all about assertion, combat and Alpha dog dominance.

A few questions in, Mrs. Clinton rose from her chair and loomed over Mr. Stephanopoulos. It was like watching someone get elbowed in a dark alley by their homeroom teacher. But her attempt to take over the show was nothing compared with her attempt to dominate the truth. For the first 30 minutes, she did not utter a single candid word.

She peddled her sham gas-tax holiday and repeated her attempt to blame Indiana's job losses on outsourcing and NAFTA. Mr. Stephanopoulos asked her to name a single economist who thinks a tax-holiday would work, and the daughter of Wellesley and Yale shoved the geeks into their lockers: "I'm not going to put my lot in with economists."

When Mr. Stephanopoulos pointed out that Paul Krugman, a New York Times columnist who usually supports Mrs. Clinton, has raised doubts about the plan, Mrs. Clinton lumped Mr. Krugman in with the Bush administration and said she wasn't going to listen to the people responsible for the last seven years.

This was shamelessness with a purpose. Mrs. Clinton signaled that she wasn't going to concede even an inch to the vast elitist conspiracy. She wasn't going to feel guilty about ignoring the evidence. She was going to stomp on it, flay it and leave it a twisted mass of jelly quivering on the ground. She was going to perform the primordial duty of an alpha dog leader -- helping one's own.

Barack Obama gave off an entirely different vibe on "Meet the Press." His campaign has been in the doldrums. He's never explained how he would transform politics, and his conventional substance is beginning to overshadow his unconventional style.

But, as Sunday's contrast made clear, Mr. Obama still seems like a human being. He still seems to return each night to some zone of normalcy where personal reflection lives. He wasn't fully candid when answering questions about the Rev. Jeremiah Wright, but some inner guardrails prevent the spin from drifting too far from the truth. Thoughtful and conversational, he doesn't seem to possess the trait that Mrs. Clinton has: automatically assuming that critics are always wrong.

Mr. Obama still possesses his talent for homeostasis, the ability to return to emotional balance and calm, even amid hysteria. His astounding composure has come across as weakness in the midst of combat with Mrs. Clinton, but it's also at the core of his promise to change politics. He vows to calm hatred and heal division.

This contrast between combat and composure defines the Democratic race. The implicit Clinton argument is that politics is an inherently nasty business. Human nature, as Mrs. Clinton said Sunday, means that progress comes only through conquest. You'd better elect a leader who can intimidate. You'd better elect someone who has given herself permission to be brutal.

Mr. Obama's campaign grows out of the longstanding reform tradition. His implicit argument is that politics doesn't have to be this way. Dishonesty and brutality aren't inevitable; they're what gets in the way. Mr. Obama's friend and supporter Cass Sunstein described the Obama ideal in The New Republic: "Obama believes that real change usually requires consensus, learning and accommodation."

That's regarded as naive drivel in parts of Camp Clinton.

Campaign issues come and go, but this is a thread running through the race. One believes in the raw assertion of power, the other the power of communication.

They are imperfect messengers for their creeds. Mrs. Clinton rails against "Wall Street money-grubbers," but her policies are often drawn from the Wall Street wing of the party. Mr. Obama talks about postpartisan compromise in the abstract, but rarely in the particular.

Still, amid the storms of the presidency, their basic worldviews would shape their presidencies. Mr. Obama is instinctively a conversationalist and community-mobilizer. Mrs. Clinton, as she says, will fight and fight. If elected, she'll have the power to take the Hobbesian struggle she perceives, and turn it into remorseless reality.