It’s one of the oldest rules in politics. And it’s one that her husband, Bill Clinton, made famous: “When you’re in a hole, stop digging!”

So why is Secretary Hillary Clinton continuing to dig away? Her book tour was bound to be rocky. With a tin ear for the nuances of young feminists, she titled her book, Hard Choices. But the Washington Post recently published Janet Harris’ column urging all liberals to “stop saying abortion is a difficult choice." If you talk like that, Harris says, you are putting the focus on the fetus. Well, we can’t do that! Difficult Choice? Hard Choices? Her very book title is off-key in the pro-abortion chorus. Even worse, Hillary Clinton famously told Newsweek in 1994 (October 31st issue) that “abortion is wrong.” She had never said it before and she has never said it since. But she said it. And that spells trouble with the Left that will not provide legal protection for a single one of the 57,000,000 unborn children whose lives have been sacrificed to choice. Then there’s young Rob Goodman’s piece in Politico. It’s titled “Duck this Dynasty.” That’s pretty clever, I’ll admit. And the argument this activist makes is most interesting.

If the Democrats hope to make an issue out of income inequality, they need to choose a leader who can make this issue resonate with young Americans who are climbing mountainous college debt and sliding into valleys of dependency. Hillary’s comment that she and Bill were “dead broke” on leaving the White House was a disaster. Her approval numbers seem to have fallen off a cliff after that. What? Did they run out of time to sell presidential pardons? Or did they run out of rich convicts to sell them to?

Goodman basically argues that the Left needs a tribune of the people to rally the Occupy Wall Street caucus, someone who can represent the Democratic wing of the Democratic Party -- as Howard Dean memorably put it.

The book launch was trouble enough, but Madame Secretary kept digging. She gave an interview to The Atlantic in which she said: “’Don’t do stupid stuff’ is not an organizing principle for a great nation.” Now, Don’t Do Stupid Stuff may not have the ring of "Don’t Give Up the Ship", but it is nonetheless the signature statement of President Barack Obama on foreign policy. It may be that his DDSS bracelet has replaced WWJD as a constant reminder to the Commander-in-Chief not to become entangled in ground wars. She was trying in an incredibly clumsy way to “distance herself” from the administration of which she was an integral part for four years. We’re getting the impression that Hillary is no longer “likable enough” to this president.

Because her husband frittered away his eight years in the White House, perhaps she has forgotten that -- as Daniel Day-Lewis reminded us in his magisterial portrayal of Lincoln -- that “the President of the United States is clothed in immense power!” If she doubts that, she need only ask survivors of Hubert Humphrey’s 1968 campaign what becomes of a top administration figure who tries to “distance” him or herself from the party’s designated leader. President Lyndon Johnson dared not show his face at his party’s 1968 convention, but he still held the whip hand as far as his harried vice president, Humphrey, was concerned. And LBJ showed that even a Lame Duck could still deliver a stunning kick.

But then there is Hillary Clinton’s amazing unforced error. Yahoo defines an unforced error for us. It is “a mistake that you make due to simply hitting the ball incorrectly (shanks, mishits) or using improper positioning,” Hillary Clinton decided recently, for some incalculable reason, to do a book review for the Washington Post’s Sunday “Outlook” section. She chose -- of all the books in the world -- Henry Kissinger’s latest bestseller: World Order. Talk about curious titling for your book. Dr. Kissinger’s opus arrives at the moment when only Antarctica seems peaceful. World Order? But at least this 432-page marvel is No. 1 in books on Diplomacy. Clinton’s own book is only an anemic No. 6 on Amazon’s listing and seems headed for the remainder stacks.

What could she have been thinking in giving Dr. Kissinger’s book a generous review? She acts like she already has her party’s 2016 nomination sewn up and is deciding to “move to the center.”

She seems not to realize that for a substantial portion of her party’s liberal base, Dr. Kissinger is an evil figure. The late Christopher Hitchens spent years -- literally years -- clamoring for Henry Kissinger to be indicted for war crimes!

Conservatives do not react to Henry Kissinger with anything like the fierce hatred of the Left. But conservatives -- while acknowledging the Harvard professor’s scintillating brilliance -- have steadfastly opposed his Realpolitik.

From 1976 onward, conservatives have insisted on a foreign policy that is both visionary and realistic. For America, conservatives believe, only the high idealism of a president like Ronald Reagan is ultimately realistic in the world.

As George W. Bush eloquently put it in his eulogy to Reagan, the Gipper said “Tear Down this Wall;” he didn’t say knock the top three bricks off it.” In the end, it proved more “realistic” to bring down the Wall than to arrange weekend visits for the captive peoples behind it.

As she struggles to regain her footing for the next few years, it may be that this paragraph will come back to haunt her, especially with Iowa’s Peace Caucus-goers:

Kissinger is a friend, and I relied on his counsel when I served as secretary of state. He checked in with me regularly, sharing astute observations about foreign leaders and sending me written reports on his travels. Though we have often seen the world and some of our challenges quite differently, and advocated different responses now and in the past, what comes through clearly in this new book is a conviction that we, and President Obama, share: a belief in the indispensability of continued American leadership in service of a just and liberal order.

Conservatives and Left-liberals alike will be scratching their heads trying to figure out why Hillary Clinton decided to publicly embrace Henry Kissinger. We will try to resist the cynicism of French Foreign Minister Talleyrand. Legend has it that when informed that the Russian ambassador had collapsed and died en route to a meeting in the Quai D’Orsay with Talleyrand, the wily Frenchman stroked his chin and said: “I wonder why he did that?”

Still, with all her other troubles, I have to ask of Hillary Clinton’s valentine to her eminent predecessor, Dr. Kissinger: “I wonder why she did that?”