The insurgent impulse is not unique to Republicans. The right has its Trump. The left has its Sanders. But last night's debate illuminated the stark contrast between Democratic insurgents and Republican insurgents.

In his debate performance, Bernie Sanders showed himself to be principled, passionate, knowledgeable, and virtuous. He argued relentlessly against the corruption of money and the plight of American workers--as he has for decades. When he had an opportunity to prick Hillary Clinton over the email scandal, Sanders chose instead to dismiss the brouhaha as a distraction from the issues that matter. He is a revolutionary in the finest tradition of high-minded American revolutionaries, from George Washington to F.D.R., who would change the world without sacrificing dignity or decency. He is, to use my grandfather's term of highest praise, a mensch.

Trump's idea of political change is less sweeping, to put it mildly. He would build a wall. He would lower taxes. He would negotiate harder with the Chinese, whatever that means. He hates Mexican immigrants. His insurgency is not principled, it is personal, and his personality differs from the Democratic insurgent's in everyway. Where Sanders is self-effacing, Trump is egomaniacal. Where Sanders is consistent, Trump is mercurial. Where Sanders is knowledgeable, Trump is ignorant. Where Sanders is "classy"--a word that Trump worships but doesn't understand--Trump is crass. Unlike Sanders, Trump never forgoes an opportunity to excoriate his opponents, and he revels in banal and puerile insults. If he had been on that stage last night instead of Bernie Sanders, the debate might have been more entertaining, but it would have been shallow, nasty, worthless. Trump is, to use my grandfather's harshest insult, a schmuck.

This does not mean that Democrats are naturally mensch-like or that Republicans are inherently schmucky. Both parties have plenty of both. But it is telling that mensches rise to the top of the Democratic Party even among anti-establishment insurgents, while would-be Republican revolutionaries are pathetically in love with a gang of schmucks.

Michael Wolraich is the author of Unreasonable Men: Theodore Roosevelt and the Republican Rebels Who Created Progressive Politics