Understanding why Mitt Romney so decisively won the first presidential debate is as important as the fact that he did. Why? Because once we know the reasons, almost everything about President Barack Obama and this election becomes clear.

First, Obama lost because he, like virtually the entire left, lives in a left-wing bubble.

Left-wing academics live in this bubble. There is no greater uniformity of thought than at our universities; their much-ballyhooed commitment to diversity is about race and ethnicity, not about ideas.

So, too, the great majority of news media people live in the same bubble, the left-wing herd that covers national and international news. Reading The New York Times, The Washington Post, the Los Angeles Times or Le Monde or listening to the BBC is essentially reading or listening to the same selection and presentation of the news.

One reason leftists talk to, read and listen to only fellow leftists is that they are certain that there is no other way to think rationally, compassionately or morally. Therefore, there is no reason to debate conservatives, let alone expose oneself to their ideas.

Obama is a man of the left. Leftism is his Weltanschauung, his value system, his way of understanding the world. Every one of the president's mentors whom we know about was a leftist, usually a radical leftist. The church he was married in and the pastor he adored were leftist. His work -- "community organizer" -- was left-wing work.

When you live in a bubble -- be it religious or political -- you cannot successfully debate opposing views. You're not even familiar with what those opposing views are. This debate was the first time in Obama's presidency -- if not his life -- that he had to defend the policies he believes in against an articulate conservative.

He couldn't.

The second reason for his defeat was that Obama lacked two things that have been essential to his popularity for the past four years.

One was a teleprompter. Most people would sound articulate if they could rely on teleprompters to speak words they and/or others wrote. But there were no teleprompters last Wednesday night.

Were a Republican president as dependent on a teleprompter as this president has been, the media constantly would report -- and mock -- the fact.

Which brings us to the news media's protection, the other thing the president was deprived of at the debate.

In the increasingly inglorious history of the mainstream (i.e., liberal) media, nothing has matched their four-year protection of this president. To cite but one of countless examples, when President George W. Bush signed the Patriot Act and incarcerated terror suspects at Guantanamo, the press was relentless in its attacks on him for allegedly undermining civil liberties. When Obama extended the Patriot Act and kept terror suspects in Guantanamo, the press was virtually silent.

A third reason for the Romney victory was the debate format. Moderator Jim Lehrer and new guidelines allowed the debaters to actually debate. The reason the liberal media have been so contemptuous of Lehrer is that, perhaps for the first time in the history of modern American presidential debates, the moderator did not attempt to dominate the proceedings. And what the left cannot control it fears.

According to Reuters, Obama spoke a full four minutes more than Romney did. But because Lehrer allowed Romney to actually respond to Obama, Romney didn't need any more time than he took.

Obama also lost because he is not intellectually deep. He is extremely bright. But he is not intellectually deep. If you read, rather than only listen to, any of his speeches -- from Berlin and Cairo until today -- you will discover how essentially empty they are. But because he never is challenged and because he delivers his largely nice-sounding vapidities so smoothly and authoritatively, many Americans are fooled.

He could not get away with this in the first debate. And though Obama surely will be much feistier and more aggressive in his second debate, if Romney is allowed to respond and challenge as he was in the first debate -- very possibly a big if -- there is no reason to believe that he will get away with his platitudes then, either.

Finally, Romney won because he understands how the economy works much better than Obama does -- and because he understands what America stands for much better than the president does.

The great unknown is whether enough Americans will come to realize all this by Election Day.