None too soon to think about the prospect of impeachment. It’s in the headlines, after all, in the wake of the guilty verdicts against Paul Manafortand the guilty pleas by Michael Cohen.

It may be claimed that none of the crimes of President Trump’s ex-campaign manager and ex-personal lawyer directly implicate the president. Not yet, anyhow — though Cohen is insisting he was directed by Trump to violate campaign-finance laws.

And Cohen is now practically begging to sing against Mr. Trump to special counsel Robert Mueller. Manafort, found guilty on Tuesday of eight counts against him, is already reported to be considering all options — and faces yet another trial next month.

No wonder the Web is fizzing with talk of impeachment.

What invites reflection, however, is not the technical definition, which is the power the Constitution grants the House of Representatives to accuse a president of treason, bribery or other high crimes or misdemeanors.

Any articles of impeachment passed by the House against Mr. Trump would go to the Senate, which then becomes the jury that would decide the president’s fate.

No, the thing to reflect on is what a serious thing impeachment is. So daunting is it that over 229 years, our country has never removed a president through a trial in the Senate.

Did Thomas Jefferson collude with the French during their quasi-war against America? What about the so-called “corrupt bargain” when the election of 1824 was thrown to the House?

That’s when House Speaker Henry Clay backed John Quincy Adams and ended up as his secretary of state. None were impeached, nor was President Ulysses Grant during the “Whiskey Ring” scandal.

Warren Harding wasn’t impeached during “Teapot Dome.” Nor was Ronald Reagan over the Iran-Contra affair. Nor George W. Bush, despite all the fury over Iraq.

Of the thousands of federal officials who’ve served over our long history, only 19 were impeached and only 11 convicted. Just two presidents — Andrew Johnson and Bill Clinton — were impeached. Both were acquitted. (Richard Nixon resigned before he could be impeached.)

When you think about it, that’s amazing. With all the scandal and controversy that has roiled our politics, the Congress has been incredibly loath to un-sheath the sword of impeachment.

The question is, why?

My own theory is that this has to do with the nature of America’s constitutional system. It ordains that the states, via the Electoral College, choose the president — and under our current system, the voters of each state choose those electors.

The selection of the president, then, is an act of self-rule in which the people are massively invested. Including, of course, the 2016 election, in which something like 138,847,000 voters turned out.

In the Electoral College, 56% of the delegates voted for Trump. To boot a president from office, especially for acts that predated his presidency, will be seen as overturning the will of the people.

This time, though, there’s a wrinkle: One party doesn’t believe the process delivered a legitimate result, mostly (but not entirely) because of the astounding margin by which Trump lost the popular vote. Never mind that it doesn’t count for beans in the constitutional sense.

Hillary Clinton won the popular vote by an incredible 2.9 million votes, more than 2 percentage points. So infuriated were the Democrats that they set out to topple the president.

If you believe, as many Democrats do, that the process wasn’t legitimate, then the bounds of acceptable “resistance” to it widen.

So a constitutional framework that bids Congress shrink from ousting a president confronts a party that lusts for the chance. Which vindicates a warning from Alexander Hamilton.

Impeachment, Hamilton warned in the Federalist papers, is bound to “agitate the passions of the whole community, and to divide it into parties.” It would “enlist all their animosities, partialities, influence and interest.”

Hamilton feared that the decision would be “regulated more by the comparative strength of parties, than by the real demonstrations of innocence or guilt.”

Smart fellow, this Hamilton (founder of The Post). He was among those who thought the Supreme Court wasn’t up to deciding the fate of an impeachment. He wanted the Senate.

Will we go there? I, for one, hope not. But I find myself thinking of Secretariat’s famous groom, Eddie Sweat, who before the big race supposedly shouted at the sky: “Get ready!”

This column first appeared in the New York Post.

Image: Secretary of War Stanton aims a cannon labeled “Congress” to defeat President Johnson.The rammer of the cannon is the Tenure of Office Bill, for the violation of which Johnson became the first president to be impeached. He was acquitted in the Senate. The Tenure of Office Bill was later ruled unconstitutional. From the Library of Congress, via Wikipedia.