Third, on a night when the moderators repeatedly challenged Sanders on his statements, raising concerns, there was one big claim they did not even question. “Whether you’re a conservative, a moderate, or a progressive,” Sanders said, “I don’t think the American people are proud that we have a president who is a pathological liar. And it does not give me pleasure to say that.”

Under any previous president, moderators would have expressed shock at such a statement. But it is so obviously true that the sitting president is a pathological liar that even moderators on Fox let the characterization stand. “Trump cannot even tell the truth as to where his father was born,” Sanders said. “It’s really that crazy. His father was born in New York; he claims he was born in Germany. If you can’t even tell the truth about where your father was born, it’s hard to believe anything he says.”

It wasn’t a perfect night.

Read: Bernie Sanders’s staffers want him to be less grumpy

Sanders was at his most disappointing when he touted a popular subsidy that would disproportionately benefit relative elites (free college tuition); was vague about how he intends to pay for his agenda; and explained why he has opposed so many free-trade agreements, which is to say, policies that increase the size of the economic pie, helping the United States afford more social-welfare spending. He sometimes impugned the motives of those who challenge the practical viability of his proposals, as if they’re all just bought-off shills.

Still, he stepped into one of the more significant filter bubbles that divide red from blue America. He was decent in his manner, pleading for comity, embracing universalist rather than identitarian language, decrying racial injustice and anti-Muslim demagoguery, and mincing no words in correctly labeling Trump a pathological liar. His strengths outshone his flaws in front of a TV audience that many Democrats have a hard time reaching, having written it off as deplorable, if not irredeemable. He showed other Democratic candidates the way forward and warmed up the Fox audience to left-wing ideas.

For having a constructive discussion despite their significant differences, Sanders and Fox deserve congratulations and that highest form of flattery: imitation.