The best tonic for those who suffered through last week's tax debate in this steamy capital is a trip to Maine -- which is where I hope to be when these words are published. Short of that, however, the recommended method for cleansing the mind of those tax vapors is reading a dandy little essay called, "The Reagan Budget: The Deficit That Didn't Have To Be."

It was written by David Boaz, the vice president of the Cato Institute, a Washington think tank with a Libertarian outlook. As a policy proposal, it is absolutely hair-raising. But it is the perfect cold spray of candor the entire tax-budget debate needs to rid itself of the sweating hypocrisy that surrounded it.

Rarely has the art of camouflage been stretched as far as it was by the Reagan administration's effort to pretend that its $98.3 billion tax hike was just the latest logical chapter in the ongoing saga of Reaganomics.

Liberal Democrats like Ted Kennedy knew it was a reversal of the earlier Reagan dogma, and embraced it. Conservative Republicans like Jack Kemp knew the same thing, and rejected it. All week the White House strained to fashion a majority of people who would ignore the obvious.

Until last month, the President argued that deep tax cuts would stimulate the economy enough to make revenues grow faster than the rate at which he proposed to allow government spending to expand. Result, no deficits.

It hasn't worked out that way. Faced with enormous deficits, he turned about and said that higher taxes would be needed along with slower spending rates in order to reduce the red ink.

The newer formulation may be closer to reality than the old, but tax hikes of the size Reagan recommended still leave the prospect of deficits in the $100 to $150 billion range for the next few years.

And that is where the Boaz prescription comes in. In a few brisk pages, he shows how to save $209 billion in domestic spending, thus eliminating the deficit and giving room for the next, scheduled tax cut.

He concentrates on the civilian side because another Cato author, Earl C. Ravenal, had previously shown how to save $204 billion in the military by protecting the United States instead of the whole world.

Understanding that Reagan and others might object to the defense cutback, Boaz shows how to get the savings needed for a balanced budget out of the civilian sector. All we have to do is give up those government activities that "restrict economic growth and competition, close off the economic system, interfere with our civil liberties or otherwise damage our society."

For example, we could save $450 million by abolishing the Nuclear Regulatory Commission. Some people criticize the NRC for being insufficiently vigilant about atomic plant safety. But as Boaz sees it, the mistake is that the NRC "absolves companies of their responsibilities" to operate safely. "Nuclear plants should be held strictly liable for any damage they do," presuming the survivors are in good enough shape to sue.

Similarly, the Forest Service and the Fish and Wildlife Service spend $2.5 billion in an "attempt to protect natural resources, but such government attempts almost always fail....Privately owned forests will be better maintained than those owned by the government."

We could save $520 million by abolishing the Immigration and Naturalization Service, because "open immigration would help the economy and save tax dollars." We could save $242 million by killing the Drug Enforcement Administration, which "harasses and imprisons businessmen and their customers who engage in the voluntary exchange of goods and services, forcing otherwise honest traders into a life of crime -- surely something an administration devoted to free enterprise should abhor."

On and on, Boaz goes, laying waste to the agencies and departments, until he hits the big-ticket items: $18 billion saved by freezing all Social Security benefits; $76 billion saved by rolling other entitlement programs back to the 1970 level, as measured by share of gross national product.

What is cleansing about this analysis is its demonstration of what would really be required to eliminate the looming deficits, assuming that defense is left untouched and the revenue base is allowed to decline on the path set by the 1981 Reagan tax bill.

Measured against such honest steps, this past week's struggle for a minor corrective tax bill can be seen as the picayune thing it was. It takes a man of Boaz' boldness to really lay bare the fiscal realities. Reagan and David Stockman only hint at the "further savings" that will be necessary to eliminate future deficits. Boaz spotlights them.

Bravo, Boaz. Let real Reaganites rejoice. They may have lost their old hero in the tax fight switcheroo. But a new one is on the scene.