Heading into this country’s fourth brush with impeachment, Republicans and Democrats should be exceedingly careful as to what they choose to define as a serious matter, and what they decide to excuse.

Experience shows that what you say now can come back later to bite you. It happens in rather strange ways that you never expected, and by means that you never foresaw.

In 1991, Bill and Hillary Clinton eagerly jumped on Anita Hill’s wagon, branding themselves and their party as defenders of women, against demonic and predatory men. This worked like a charm until six years later, when Bill had been outed as one of the predators. At that point, their supporters suddenly had to change their tune: men were to be believed when women accused them; women were known to have lied when it suited their purpose. Besides, how did we know that these women weren’t sluts?

"Gentlemen always lied about sex," said Arthur M. Schlesinger, skirting the question of who was a gentleman. Feminists backed their good friend who supported abortion, and a whole flock of artists and writers said we should all be more worldly about promiscuity, the way that they all were in France.

This carried the day, Bill was acquitted, and Hillary had launched herself into a seat in the Senate from the state of New York, from which she intended, in the not-too-far future, to return to the White House in her own right.

It was sixteen years later, and Hillary was making her second attempt at the presidency, when fate threw her an unlikely curveball. She was facing the one man in the country who was more Bill than even Bill. He was just as likely as Bill to be pouncing on women (at least, by his own account), as he was as unlikely as Bill was to take no for an answer — described as "hands on."

When a tape surfaced days before the second debate of her rival telling a friend that when ‘you’re a star, you can grab women anywhere,’ it should have been the final knockout. She was unaware that he had invited five of Bill’s accusers — some of whom she had personally bullied and vilified — to sit in the audience, and in the front row.

About three weeks later, her opponent, to his own surprise, was elected as the forty-fifth president, and she was retired to Chappaqua and to history. Her husband and those who defended him in 1998-99 had all done their work all too well. Americans had indeed become more casual about promiscuity, to say nothing of more willing to question female accusers.

This tale and its ending should be food for thought, Democrats in 1998-99 had been all too enthused in defending their president. Instead of confessing his conduct was wrong, but not on a scale to demand his removal, they said what he’d done had not been important. They argued that, insofar as his infidelity revealed his humanity, it was almost an asset: better to be a warm-blooded lover of life and its pleasures than a censorious scold like Ken Starr.

In short, they had normalized lying and lechery, thinking that Bill was a one-off as president; they never dreamed that another outsized liar and lecher would emerge on the other side, and so soon, or that people's lax attitudes toward his promiscuity would thwart Hillary Clinton’s last run at history.

With this in mind, both sides in the coming impeachment dramatics should try hard to rein themselves in. Democrats should not seem too shocked at lying and lechery, given that in recent times they called them unimportant. Republicans should sadly admit to the sins of their president while arguing that no crimes were involved. Excess either way could come back to bite them. Clinton herself can tell you that it’s true.