They say we are products of our environments, but Obama, the sojourner, seems to go through various situations without being overly touched by them. Over the past two years, he has been the subject of nearly unparalleled public worship, but far from getting drunk on it, he has become less grandiloquent as the campaign has gone along.

When Bill Clinton campaigned, he tried to seduce his audiences. But at Obama rallies, the candidate is the wooed not the wooer. He doesn’t seem to need the audience’s love. But they need his. The audiences hunger for his affection, while he is calm, appreciative and didactic.

He doesn’t have F.D.R.’s joyful nature or Reagan’s happy outlook, but he is analytical. That’s why this William Ayers business doesn’t stick. He may be liberal, but he is never wild. His family is bourgeois. His instinct is to flee the revolutionary gesture in favor of the six-point plan.

This was not evident back in the “fierce urgency of now” days, but it is now. And it is easy to sketch out a scenario in which he could be a great president. He would be untroubled by self-destructive demons or indiscipline. With that cool manner, he would see reality unfiltered. He could gather  already has gathered  some of the smartest minds in public policy, and, untroubled by intellectual insecurity, he could give them free rein. Though he is young, it is easy to imagine him at the cabinet table, leading a subtle discussion of some long-term problem.

Of course, it’s also easy to imagine a scenario in which he is not an island of rationality in a sea of tumult, but simply an island. New presidents are often amazed by how much they are disobeyed, by how often passive-aggressiveness frustrates their plans.

It could be that Obama will be an observer, not a leader. Rather than throwing himself passionately into his causes, he will stand back. Congressional leaders, put off by his supposed intellectual superiority, will just go their own way. Lost in his own nuance, he will be passive and ineffectual. Lack of passion will produce lack of courage. The Obama greatness will give way to the Obama anti-climax.

We can each guess how the story ends. But over the past two years, Obama has clearly worn well with voters. Far from a celebrity fad, he is self-contained, self-controlled and maybe even a little dull.