As usual, Mark Twain had it right when he reputedly said, “History doesn’t repeat itself but it often rhymes.” He might have been envisioning the current Clinton drama and whether the nation learned anything from the last one.

Seventeen years after the United States Senate rejected two articles of impeachment against President Bill Clinton, America is getting a mulligan. It’s getting another chance to prove we really are a nation of laws, that rich and poor, powerful and weak — and the Clintons — stand equal before a blindfolded Justice.

Because this second test comes from Hillary Clinton, and also involves probable criminal actions, it is imperative that we get it right this time. The nation is still paying a big price for getting it wrong in 1999.

By beating charges of which he was clearly guilty, Bill Clinton proved that equal justice is an ideal, not a fact. He was acquitted of perjury and obstruction because he was too big and popular to convict over actions that grew out of a sex scandal.

One inevitable result was a boom of political corruption as pols up and down the food chain vied to see whether they also were too important to convict. From coast to coast, the corrosive result is obvious as prosecutors lock up scores of officials, only to see many replaced with more crooks. Overall crime in America is down, but it’s soaring in the halls of government.

Which brings us back to Hillary Clinton or, more accurately, her case brings us back to the question of whether we are committed to a single standard of justice. Are we a nation of laws, or is that just another fuddy-duddy aspiration of the Founders that modern sophisticates should dump?

While Clinton has not been charged, enough is known about the FBI’s criminal investigation of her home-brew server and reckless handling of national security secrets to reasonably conclude that prosecution is warranted.

Once the people say integrity is optional, the nation is lost. An America that gives up on integrity would not be America anymore.

A thorough investigation also would have looked at whether she sold favors as secretary of state to firms and individuals who paid her husband millions for speeches and contributed millions more to the family foundation. But that angle apparently never was even considered.

It is a tragedy, then, of the first order that Clinton will probably never face the music on either matter. President Obama’s endorsement of her was a virtual “all clear” signal to the Justice Department as well as to hesitant Democratic voters.

Obama’s gushing assertion that Clinton has “the courage, the compassion and the heart to get the job done” demolishes any hope that the FBI probe would turn on the merits.

With Donald Trump seemingly bent on self-destruction, that leaves only two hurdles remaining before another conniving Clinton occupies the Oval Office.

The first hurdle is whether FBI Director James Comey and agents on the case quietly accept a “stand down” order. Their law-enforcement training could lead them to go along as good soldiers, or it could lead to public objections and a “Saturday-night massacre” scenario at Justice, with Obama playing ­Richard Nixon.

That outcome is unlikely, if only because the career price would be too high for Comey and the agents involved, especially with the liberal media denouncing them as racists, misogynists, blah, blah, blah.

Voters are the second and last hurdle. Assuming Clinton never has to offer a defense to the e-mails and server beyond the tortured lies she’s told in public, Americans must decide whether she, like her husband, is too big and popular for ordinary standards of justice.

If she becomes president despite the high probability that she committed the same crimes that have sent others to prison or infamy, it will be certain that we have cut our roots to the Founders, and that John Adams was wrong.

“We are a nation of laws and not of men,” the second president said. Not anymore. We would now be a nation whose laws are void if your name is Clinton.

As before, there would be copycats in politics, business and society at large, but who would stop them and declare that the laws matter? There would be nobody left.

Once the people say integrity is optional, the nation is lost. An America that gives up on integrity would not be America anymore.

Donor is a pain in the cash for Blas

For once, you can be sure Mayor de Blasio is telling the truth. After one of his big donors pleaded guilty to conspiracy charges, de Blasio told reporters, “I wish I never met the guy.”

No kidding.

“The guy” is Jona Rechnitz, a businessman who admits to being the bag man — literally — in the alleged kickback scheme involving Norman Seabrook, former head of the correction officers union. According to federal charges, Seabrook wanted to be paid for investing union money in a hedge fund, and Rechnitz set up a deal for Seabrook to secretly get up to $150,000 a year if he invested $20 million in a Platinum Partners fund.

Rechnitz admitted he delivered a down payment of $60,000 to Seabrook in a Salvatore Ferragamo bag.

Now that Rechnitz is talking and Seabrook and hedge funder Murray Huberfeld have been charged, investigators are likely focusing more on the mayor and what Rechnitz knows about him.

It could be a lot. He and his wife each contributed the maximum $4,950 to de Blasio’s 2013 campaign and gathered $40,000 more from other supporters. Rechnitz also gave $50,000 to the mayor’s political slush fund, the Campaign for One New York.

The fund is at the heart of the federal probe because nearly all of its $4.36 million came from big donors who had pending business at City Hall.

After announcing the charges against Seabrook and Huberfeld, US Attorney Preet Bharara promised more to come. “We intend to be as aggressive as ever in exposing corruption wherever we find it, and it is too bad that we seem to find it everywhere we look,” he said. “You can expect to see me again.”

You can be sure he’s telling the truth, too.

Department of Education’s gibberish on Brooklyn pre-K deal

The jabberwocky of the week comes from a city flack: “We repurposed a valuable city-owned property and renovated it into a state-of-the-art facility to provide additional free, full-day, high-quality pre-K seats in a high-demand community.”

Translation: Educrats spent $6.5 million to fix up a tiny Brooklyn storefront that will hold no more than 18 pre-K students. As The Post reports, that’s $362,222 per tot — if all 18 show up.

Trump stumping – for Hill

Reader Gary Mottola worries that Donald Trump is screwing up big time.

“It’s been said that the Clintons have been lucky in their enemies, and they could hit the jackpot with Trump,” he writes. “He may end up being remembered as the idiot who got Hillary elected in a year where she should be easy to beat.”