Presidential debates are, like pretty much the entire campaign, an artificial situation demanding performance skills that don't necessarily have anything to do with governing. And yet, in the right circumstances they can reveal the candidates for who they really are. That's certainly what happened Monday night.

Now I'm a liberal, and like everyone else I watched the debate through the filter of my own biases. But even if you didn't think Hillary Clinton pummeled Donald Trump into a mushy orange husk, it was hard to avoid the conclusion that both candidates showed true versions of themselves. It just happened that in this particular forum, Clinton's true self has some advantages over Trump's true self. That's in spite of the fact that there are some contexts in which he's a superior performer to her. A debate just isn't one of them.

Debates demand preparation, and for her whole life, Clinton has been nothing if not prepared. She may not dazzle you with improvisational genius, but she will have spent more time doing her homework than anyone else in class (it's no accident that people keep comparing her to Hermione Granger from Harry Potter). She's ready to discuss any policy area, and she's usually at her best when speaking extemporaneously. And once she makes a plan, she knows how to stick to it.

Trump, on the other hand, doesn't really care about policy, has a short attention span, and wasn't interested in practicing for the debate — a fact leaked out to numerous reporters. Despite suspicions that it was merely spin meant to lower expectations, it sure seems like it was true.

And just as we saw Clinton the dutiful student, in Trump we saw a man with a fragile ego intent on making points that won't do anything to convince undecided voters he should be president. For about the first five minutes, he seemed like the more subdued, reasonable Trump his advisers have tried to present. But the real Trump quickly emerged.

Clinton obviously wanted to bait him, and she succeeded — again and again, he interrupted her to protest that something she was saying about him wasn't true, even though she was almost always right. But what's really important was the nature of the criticisms and the nature of his defenses. It has become clear over the course of this campaign that there's almost nothing more important to Trump than convincing himself and others that he's not a sucker. No, he's the one who makes other people into suckers: He gets the better of them in negotiations, he shows he's more manly than them, he has more money and status and a hotter wife than them.

And in the debate, we saw this again and again. This is his chief complaint about other countries like China and Mexico: When low-wage jobs move overseas or we have a trade deficit, what it means is that somebody else has taken advantage of us. And whenever Clinton criticized him for something in his private life or business career, the essence of Trump's defense was that it was okay, because he wasn't the sucker. He would make that assertion even when it proved exactly the point Clinton was trying to make.

Consider:

She noted that before the housing crash that precipitated the Great Recession, Trump had publicly expressed hope that the bubble would burst so he could swoop in and buy real estate on the cheap. He interrupted her to say, "That's called business, by the way" — probably not the expression of compassion his advisers would have hoped for.

He bragged about his income, saying that in his financial disclosure, "the income is filed at $694 million for this past year, $694 million. If you would have told me I was going to make that 15 or 20 years ago, I would have been very surprised. But that's the kind of thinking that our country needs. When we have a country that's doing so badly, that's being ripped off by every single country in the world, it's the kind of thinking that our country needs."

When Clinton noted that in the only tax returns publicly released by Trump — from many years ago when he was applying for a casino license — he paid no federal income tax, Trump jumped in to say, "That makes me smart."

He said, "I am very underleveraged. I have a great company. I have a tremendous income. And the reason I say that is not in a braggadocious way. It's because it's about time that this country had somebody running it that has an idea about money."

When Clinton suggested again that Trump may not have paid any income tax in recent years, he replied, "It would be squandered too, believe me," which seemed to concede that her accusation was accurate.

When Clinton accused him of not paying people who did work for him (which has been the cause of multiple lawsuits against Trump), he said, "Maybe he didn't do a good job and I was unsatisfied with his work. Which our country should do, too." So he also admitted that he stiffs contractors.

When Clinton mentioned his bankruptcies, Trump said, "I take advantage of the laws of the nation because I'm running a company. My obligation right now is to do well for myself, my family, my employees, for my companies. And that's what I do."

In response to Clinton mentioning a discrimination lawsuit the government initiated against him and his father, Trump said, "We settled the suit with zero — with no admission of guilt. It was very easy to do." He didn't defend himself against the charges, but instead tried to argue that by settling the suit, he won.

He repeated again that "we should have taken the oil" when we left Iraq.

He noted that with regard to NATO, "we're defending them, and they should at least be paying us what they're supposed to be paying by treaty and contract"

There are times when it appears that Trump still cares more about being seen as a shrewd businessman than about being seen as a potential president. Which is perhaps understandable, since he's been a businessman for decades — and one whose business depends on creating the public appearance of success. But in order to succeed at this debate, he would have had to tamp down his natural impulses and become someone he's deeply uncomfortable being. We don't know if he'll be able to do that in the upcoming two debates, but he certainly couldn't do it Monday night.

And Hillary Clinton? All she had to do in order to succeed was be herself.