NEW YORK (CNN/Money) - The terrorists on 9/11 did not succeed in one crucial way: they did not permanently cripple the U.S. economy. They did knock an economy that was already on its knees, flat on its back, but the economy is on its feet again and moving forward.

I think of the economy like a person who caught a major illness, like pneumonia, and while she was in the hospital had the extraordinarily bad luck of tripping and breaking her leg. The "pneumonia" that the U.S. economy caught was due largely to the bursting stock market bubble of the late 1990's, the broken leg was the aftermath of the 9/11 attacks: massive layoffs at the airlines, a plunging stock market, businesses afraid to take risks.

The patient is out of the hospital now, but not 100 percent recovered. After all, jobs STILL refuse to grow, and that's a sign her health is still not robust.

But, more importantly, long after the job-creating engine is chugging along at full speed again, 9/11 will leave its mark because the economy is on a different path than it would have been otherwise.

The U.S. has embarked on a global initiative to fight terrorists, whether it's sending troops to track down Al Qaeda in the hills of Pakistan or "shocking and aweing" Saddam's forces in Baghdad. The budget deficit is growing in no small part due to the cost of fighting wars in Iraq and Afghanistan. Financial markets are constantly looking over their shoulders for the latest news on terror attacks or Osama Bin Laden tapes.

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The world has changed and this has important implications for the economy. A bigger budget deficit can mean higher long-term interest rates. That's a cost on consumers when they pay higher mortgage rates and on businesses when they pay higher rates to finance investment. The more money we spend on defense and on reconstruction the less we have to spend on education, new highways, rebuilding the electric grid -- all important to maintaining the competitiveness and productivity of the economy.

Allen Sinai of Decision Economics Inc. says the 9/11 attacks didn't kill the economy, but did leave it underperforming. He has no doubt that businesses would have invested more and hired more had it not been for the additional damage that the attacks did to the economy -- especially since they were accompanied by the endless string of corporate scandals that haunt the markets still.

And he says that 9/11 has not yet run its course because of the rising deficit, the growing debt burden, and because the end to U.S. commitments in Iraq and Afghanistan cannot yet be seen. He says we are in a cyclical upswing now, but the longer view of 9/11 and its aftermath is troubling.

The supply-side doctors within the administration and without aren't troubled because they say economy is getting the right medicine: big tax cuts they say are boosting consumer spending and manufacturers' orders now, and will lead to jobs growth soon. That in turn will cause so much growth in the economy and in tax revenues that the deficit will start dwindling.

Those outside the supply-side camp seem to be a bit more worried that once this summer's child tax credit checks are spent, the economy will need another dose of medicine -- more tax cuts or more rate cuts. And with the deficit already near record highs, they fear more tax cuts won't be possible. Or that Federal Reserve cuts in short-term rates will be ineffectual if a rising budget deficit is putting upward pressure on long-term rates.

Given time to heal, given a period of respite when it's not faced with all the traumas of the past two years -- terror attack, tech collapse, Enronitis, SARS (where are the locusts?!!) -- the economy can surely get back to where it was in the late 90s: pumping out jobs and plumping up profits.

As we look back to 9/11 and look into the new future we face as a result of the attacks that day, we can only wonder how long will it take to recapture that golden era and how much harder will it be now that we carry our new burdens. And we can be thankful that we have an economy with a strong immune system, and a tremendous will to survive and prosper. Any good doctor will tell you that's crucial for any patient trying to make a full recovery.  

Kathleen Hays anchors CNN Money Morning and The FlipSide, airing Monday to Friday on CNNfn. As part of CNN's Business News team, she is also a regular contributor to Lou Dobbs Tonight.