For all their shared views, Hillary Clinton and Bernie Sanders have come to this presidential contest with very different theories of how to command the presidency, driven by the Democratic schools in which they grew up and prospered.
In Sunday's presidential debate, Clinton demonstrated her pragmatic positioning, which caused her continued grief as Sanders hammered her on positions she has taken that date back to the more centrist 1990s. Sanders demonstrated his inflexible ideological bent, which caused him grief as Clinton hammered him on choosing purity even when that meant opposing steps such as money for the auto industry bailout on which so many jobs in Michigan depended.
The Democratic debate was nowhere near as confrontational as Thursday's Republican gathering, with its unintelligible shouting and references to candidate anatomy, but it represented the best honing of counter-arguments by one candidate against the other in the party's long presidential contest.
Clinton pushed Sanders on his defense of the gun industry, making him appear hypocritical given his regular condemnation of corporate misconduct.
"You talk about corporate greed?" she asked Sanders. "The gun manufacturers sell guns to make as much money as they can make."
And Sanders tied together several Clinton administration programs — trade agreements, anti-crime bills and welfare reform — to suggest that Hillary Clinton had sold out the liberal principles to which he feels a Democrat should adhere.
"There was a bill called — so-called, it had a long title to it — welfare reform bill. And this bill really was a bill that scapegoated the poorest people in this country. I strongly opposed that legislation. Secretary Clinton had a different position then," he said.
Despite Sunday being the most openly contentious Democratic debate of the season, both candidates routinely responded to each other by using the word "agree" — underscoring the fact that both are essentially liberal to different degrees.
"Well, I think we are in vigorous agreement on this," Clinton said at one point after a Sanders dissection of Wall Street's ills.
That comity appeared most notably on the lead poisoning affecting the city of Flint. Democrats held the debate here to highlight the crisis still affecting the city. Both candidates called for the impeachment or resignation of Michigan Gov. Rick Snyder, who they blamed for the slow reaction that allowed contaminated water to be used for a long period before residents were alerted to its dangers. Both candidates said the Environmental Protection Agency's role should be investigated.
Still, these candidates were formed politically in very different times and places, so it's not surprising that on a range of issues they have come to different conclusions about both the role of government in Americans' lives and the nature of political change.
Sanders rose through municipal and congressional politics in liberal Vermont; he describes himself as a democratic socialist and has been an independent for the entirety of his political career. By bent and personality, he believes that if his circle of supporters can expand enough, they can wash over the political system like a tidal wave that rips existing structures from the ground.
Clinton started as a "Goldwater Girl," moved to the left in college but quickly found herself in Arkansas, where liberalism had a stink to it. She fought alongside her husband in gubernatorial and presidential races in which Democrats were required by the nation's demographics to hew to the center.
He calls for a political revolution, with a sizable expansion of government into healthcare, college costs and economic decisions, to name a few.
Clinton, by contrast, has settled on the notion that the president should "break down barriers," which suggests that subsequent accomplishment is driven by the individual.
The difference was obvious in a discussion of climate change and the oil and gas extraction system called fracking.
"This is a national crisis," Sanders said. "And I talk to scientists who tell me that fracking is doing terrible things to water systems all over this country. We have gotta be bold now. We gotta transform our energy system to energy efficiency and sustainable energy. We've gotta do it yesterday."
When Clinton's turn came she emphasized cooperation to accomplish the same goals.
"I've already said we are taking away the subsidies for oil and gas, but it is important that people understand that a president can't go ordering folks around," she said. "Our system doesn't permit that. I am going to set the goals. I will push everybody as hard as I can to achieve those goals."
Throughout the debate, both candidates reflected the narrowing course of the campaign as it pushes toward a nomination for one of them — the most probable, at this time, being Clinton.
Sanders, trailing badly in public polls of a state where he must win, was more urgent than in previous debates, attacking Clinton over trade, another of the 1990s-era policies he holds in contempt. Clinton has acknowledged that the North American Free Trade Agreement cost American jobs; Sanders insisted that if she is elected president, she will return to approving trade deals that he calls dangerous.
If he was arguing Clinton had demonstrated too much political flexibility, she was arguing that he was too ideologically rigid. She noted in several harsh exchanges that he had opposed the Export-Import Bank, which helps American companies sell goods overseas; he reinforced his inflexibility by saying that while the bank helped some small businesses, he objected to the financial guarantees it makes available to large companies.
She excoriated his opposition to the auto bailout, which he declined to support because it was included in a measure that also helped Wall Street firms that he did not want taxpayers to aid.
In pounding on the auto bailout, she hit him on the same topic that President Obama used against his 2012 opponent, Republican Mitt Romney. She framed Sanders' opposition as disloyalty to Obama, a strategy she has used successfully to keep African American voters in her camp.
In their lengthy discussion, as in the entire long campaign, Clinton and Sanders made clear that differences among Democrats that have been papered over during the Obama years are now fully out in the open. Whichever of the candidates makes it first to the finish line, that debate will not end soon.