Bernie Sanders has all the upsides and all the downsides of a political outsider. Hillary Clinton has all the upsides and all the downsides of a political insider.

That was the main takeaway from MSNBC's Democratic debate on Thursday, which was the best debate, on either side of the aisle, aired during this presidential cycle. With Martin O'Malley out of the race, it was down to Sanders and Clinton. Both candidates turned in their finest, most contrasting performances of any debate yet — and they offered voters a very clear choice on their different visions of how politics works.

Clinton, for the first time, made a full-throated case for her political realism. "I'm not making promises that I cannot keep," she said, taking a clear shot at Sanders. Later in the debate, Clinton noted that she was besting Sanders in endorsements from his home state of Vermont — not to mention the rest of the Democratic Party.

"I think it's because they've worked with me, they've seen what I do," she said. "They want me as their partner in the White House."

Sanders was unfazed. "She has the entire establishment or almost the entire establishment behind her," he shot back. "That's a fact. I don't deny it. I'm pretty proud that we have over a million people who have contributed to our campaign averaging 27 bucks a piece."

The exchange encapsulated both the MSNBC debate and the Democratic primary itself. Clinton knows how to work the system — she's better informed, better connected, and more strategic. Sanders is untainted by the system — he's less corrupted, less conflicted, and less disillusioned.

Clinton and Sanders's worst moments were revealing

Both candidates struggled at different points during the debate, and the nature of their missteps was telling. For Clinton, it was a question about the speaking fees she took from Goldman Sachs — about $675,000 for three speeches.

Lloyd Blankfein of Goldman Sachs showing hatred and fear of Hillary Clinton at the 2014 Clinton Global Initiative pic.twitter.com/2H1zcoi55j — David Frum (@davidfrum) February 5, 2016

Clinton has no good answer on this question because there is no good answer for this question, at least not in the Democratic primary.

If Donald Trump was asked this question, he would give the honest answer — it's a YUGE amount of money, and for almost no work, who wouldn't take it? — and drop the mic amidst cacophonous cheers. But that answer won't work among liberals, and it definitely won't work with Bernie Sanders standing three feet away.

The answer Clinton chose instead — a long recitation of her record calling for tougher regulation of Wall Street — dodged the actual allegation. The concern is not that Wall Street has given Clinton money and, in return, she has promised them a deregulatory bonanza; it's that Wall Street has given Clinton money, and has bought itself a warm relationship with her, and so she is overly influenced by their view of the world. Until Clinton can bring herself to admit the force of this critique, she can't begin to convincingly rebut it.

Sanders's failure, by contrast, extended across the debate's entire foreign policy section. The energy, clarity, and moral force he brings to questions of economic fairness and political justice sag when the conversation turns to international affairs. He doesn't give the impression of being deeply informed or even particularly interested — and that's a scary quality in a potential president.

The difference between Sanders on topics he knows and is passionate about and his FP answers is really striking. — Christopher Hayes (@chrislhayes) February 5, 2016

Sanders's disinterest led to Clinton's best line of the night. Amidst a question about President Obama's escalation of the war against ISIS, Sanders skipped past the specifics, saying simply, "Let me agree with much of what the secretary said," and then pivoted to ground he's more comfortable on — attacking her 2002 vote to authorize the Iraq War.

But Clinton was ready. "A vote in 2002 is not a plan to defeat ISIS," she replied. "We have to look at the threats that we face right now, and we have to be prepared to take them on and defeat them." Sanders didn't have much of a response.

not surprising but still noteworthy: Clinton aides almost obsessively focused on bringing spin room convo to debate's foreign policy section — Sam Stein (@samsteinhp) February 5, 2016

There's a reason everyone hates Washington. There's a reason it works the way it does.

Clinton's problem is that her mastery of the political system has been attained by decades of compromises with it, and by a thorough absorption of its mores and customs. Her best answer on her speaking fees was, in essence, everybody does it. "When I left the secretary of state's office, like so many former officials — military leaders, journalists, others — I did go on the speaking circuit," she said.

She's right that there was nothing unusual, for Washington, in what she did — save for the sums she commanded, which were astounding. But voters aren't placated by being reminded that so many ex-government officials pad their incomes by speaking to corporations. That's one of the things they hate about Washington.

Clinton's efforts to separate herself from the political system come off as tinny and insulting. "Senator Sanders is the only person who would characterize me, a woman running to be the first woman president, as exemplifying the establishment," she said.

It takes nothing away from the historic nature of her candidacy to say that everyone would characterize Clinton — a former first lady, senator, secretary of state, and Democratic frontrunner — as exemplifying the establishment. Clinton's protestations to the contrary are absurd.

Sanders's problem, meanwhile, is that his purity has been preserved at the cost of his effectiveness. Though Sanders has served in Congress for more than 20 years, he's only been the lead sponsor of three bills that have been signed into law. His carefully maintained distance from the Democratic Party — evident both in his refusal to call himself a Democrat and in his colleagues' refusal to endorse him — shows the difficulties he would have working with members of his own party, to say nothing of the climb it will be for an avowed socialist to find Republican support in Congress.

And where Clinton's experience gives her deep knowledge of virtually every facet of American policymaking, Sanders's career has let him focus on the issues he cares about, and left him poorly informed on international affairs.

Which is all to say that Clinton has the benefits and drawbacks of an insider, and Sanders has the benefits and drawbacks of an outsider. Her view of the political system is realistic, her knowledge of the issues is deep, and her social ties are strong. All these qualities would likely make her an effective president. But they also mean she's captured by the political system, and that she is implicated in virtually everything Americans hate about it.

Sanders's view of the political system is idealistic, his ideas are unbounded by pragmatic concerns and interest group objections, and his calls for political revolution are thrilling. All these qualities make him an inspiring candidate. But they also mean he'll be perceived as an enemy by the very system he intends to lead, and that his promises of sweeping change might collapse into total disappointment.