Perot is in and out and in again. Clinton, once a soldier in the ideological army of leftist George McGovern, fashions himself a moderate. And President Bush, once an advocate of abortion-rights, now supports a constitutional amendment criminalizing that same procedure.

What would presidential politics be without its born agains, its changes of heart--its flip-flops?

"Flip-flop:" the Random House definition reads, "a sudden or unexpected reversal, as of direction, belief, attitude or policy."

"The opposition," it uses by way of example, "claimed that the president had flip-flopped on certain issues."

Looking for current examples? This week was one for the record book of reversals.

In perhaps the greatest flip-flop-flip-agains in political history, Texas billionaire Rose Perot re-entered the race for the presidency. As an undeclared candidate, Perot led in the polls consistently until his "grassroots" movements hit the brick wall.

Saying that he cannot resist the call of his volunteers, though, Perot pledged run on. He has stunned the experts with his popularity and pulled the rug out from his volunteers. Now, it seems, he's brushed the rug off and laid it back on the floor.

"Perot himself is nothing more than a walking bundle of contradictions and flip flops," moans Associate Professor of Government Mark A. Peterson, who teaches a course in the American presidency.

Of course, Perot's lamentations of past "mistakes"(read: lies) is no rarity.

Bush, for example, denied to the very last that he would summon his old friend and partner in fish James A. Baker III to run the crumbling White House. When the move was actually made, though it was business as usual. No mention of the earlier denials. White House reporters didn't even bother to ask.

But there is something more precious about a genuine, lips-twitching, mouth-frothing, nosegrowing flip-flop. Real flip-flops have a depth of irony and lunacy that make them unusual. They throw journalists, who never satisfy the urge to communicate the two-faced nature of politics, into a frenzy.

And flip-flops are a cherished tradition. They are an art pioneers by the earliest pioneers of American liberty.

Thomas Jefferson, for example, emphatically opposed wide power for the president, warning of demagoguery. That changed, however, when Jefferson himself was elected to the office.

When the French put a huge piece of real estate called Louisiana on the market in 1803, Jefferson, without seeking Congressional approval, exceeded and thus expanded his executive authority to make the purchase.

Jefferson the idealist won the hearts of journalists forever by declaring that he "should not hesitate for the moment" to defend right of newspapers over the right of government.