FILE - In this Sept. 16, 2015 file photo, Republican presidential candidates, former Florida Gov. Jeb Bush, right, and Donald Trump both speak during the CNN Republican presidential debate at the Ronald Reagan Presidential Library and Museum in Simi Valley, Calif. (Mark J. Terrill/AP)

Danielle Allen is a political theorist at Harvard University and a contributing columnist for The Post.

Dear Jeb Bush,

I’ve read that you are resting, getting some exercise and writing thank-you notes. I can understand that. But you are a public servant, and there is an epic battle raging for your country’s soul.

This is just to say you remind me of Achilles. Forgive me. I’m a classicist. Those ancient myths haunt my memory.

In the Trojan War, lion-hearted Achilles was the greatest fighter. But he got in a tangle with boastful, authoritarian, loutish Agamemnon, who stole his battle prize. In the face of the theft, Achilles retired from the field and refused to fight, sulking in his tent by the ships. In his absence, the Greeks began to fall back before the Trojan onslaught. Achilles chose to send his protégé, Patroclus, to assist his side. Brave Patroclus turned the tide of battle back again, but then was killed.

Florida and Ohio are the next battlegrounds for breaking Donald Trump’s momentum. Marco Rubio needs your help in your home state, regardless of whether that is as a prospective nominee for the Republican Party or simply as part of the resistance to Trump. There are probably many people saying this to you in private. Perhaps it doesn’t help to have someone say it in public. But I have no other way to communicate with you.

Besides, part of what is so frustrating to so many people these days is quiet, backroom conversations. In this letter, I am one voter speaking to another, urging you to help your friend turn the tide. I am doing it in public, forthrightly, because I consider Trump a formidable threat to our equally shared liberties.

Protégés are not always grateful, I recognize (I here publicly apologize to all of my own mentors whom I have failed to thank appropriately), but sometimes the stakes are high enough that (to switch metaphors) one just has to overlook the failings of the prodigal son. Right now, the stakes are that high.

Trump does not respect constitutionalism. He traffics in falsehood, including about his own business success. He has tolerated white supremacists as allies. Few of us would want our children to watch him on TV, where he has the power to shape the nation’s soul.

In Homer’s tale of the Trojan War, Patroclus cannot, it turns out, fight alone. He dies, and Achilles goes raging back to battle, single-handedly achieving victory for the Greeks. But that isn’t going to happen this time. If the Republican Party breaks, and needs another candidate, I suppose people might turn to you, but it seems pretty unlikely. And anyway, there is just too much saviorism out and about these days. It’s past time for us all to figure out how to do things together again — through shared efforts, works undertaken collaboratively, humble acts of democratic partnership. None of us can meet the economic, social and security challenges we face in our own person.

In his State of the Union address in January, President Obama expressed as one of the few regrets of his presidency that “the rancor and suspicion between the parties has gotten worse instead of better.” He continued: “I have no doubt a president with the gifts of Lincoln or Roosevelt might have better bridged the divide, and I guarantee I’ll keep trying to be better so long as I hold this office.”

I admire the president tremendously, but here I think he revealed a serious error in his approach. Psychologists tell us that it’s not the students who think that smartness is innate who do best but those who think that smartness is the result of hard work. Bridging our partisan divides won’t come from any of us “being better” and expecting that somehow in our person we can resolve the rancor. We have to do the work of actually building conversations that put people on different sides of the question in the same room, not just when we get to the moment of a decision but before then, when there aren’t things at stake.

That we need this kind of hard, conversation-building work is not just true in politics but in other sectors, too. Let me offer universities as an example. I think it’s long past time for universities to figure out how to make spaces for progressive and conservative streams of discourse to flow together. Bridging the divide will come only from all of us doing the work of collaborating, going at problems as partners, not riding in like solipsistic epic heroes. (For that matter, the Senate’s approach to the Supreme Court vacancy is also an example of this shortsighted solipsism.)

In your case, the epic teamwork that still awaits you is the job of stopping Trump. Rubio can’t do that by himself. John Kasich can’t do that by himself. Even Ted Cruz probably can’t do that by himself. March 15 is the next big battle. Can you help turn the tide in Florida?

My friends here on the Democratic side of the line may well skewer me for writing this letter, but I am writing anyway.

Truly, we, the people, need you.

Yours sincerely,

Danielle Allen