(FORTUNE Magazine) – Six months ago Federal Reserve Chairman Alan Greenspan vowed to slow the economy. For a while, all signs showed that he had. Wall Street cooled, housing prices retreated, and retail sales declined. Then last month the unexpected happened. The economy defied even the most optimistic forecast: GDP exploded, soaring at an annual rate of 5.3% in the second quarter. Instead of getting tough at the August Fed meeting, Greenspan left interest rates alone. That left many wondering if our fearless Fed leader had lost it.

On the surface Greenspan's actions were, well, puzzling. Last quarter's GDP growth was on top of a robust 4.8% pop the previous quarter. Industrial production climbed 5.8% over the past year. Consumer confidence remains resilient as ever, and retail sales are growing again. Not exactly the formula for a slow-down.

Those numbers, however, mask the true story. If you parse them, you'll see that Greenspan is deftly executing his much-vaunted soft landing. Though the rate of growth hasn't changed, its composition has: Consumer spending increased at only half the rate of the previous quarter, while business spending clocked double-digit growth rates for the second time in a row (the largest bump since before the 1997 Asia crisis). Today business spending on equipment is at its highest level ever as a share of GDP.

What's behind the shift? Faced with higher mortgage and credit card payments and a lackluster stock market, consumers are spending more conservatively. Throw in the deterioration of the housing market, and suddenly the three-year spending spree seems over. Although businesses are facing the same interest rates, they're securing cheap credit from foreign investors parking their money in the U.S. They are pretty much forced to do so. With a strong dollar and relatively high labor costs, firms have no choice but to spend on new technology and equipment that can raise productivity, reduce costs, and help them compete globally.

That combination adds up to one thing: Moderate economic growth should continue to propel this expansion. That's because business spending has a different effect on the economy than consumer spending, which, unchecked, could cause rapid inflation. When businesses invest in technology and equipment, they increase their capacity and the productivity of their work force. That in turn keeps a lid on inflation by letting wages rise without forcing businesses to increase the prices they charge. As long as consumer spending doesn't completely dry up, there's not much to endanger economic growth.

Though the Fed has achieved its goal, Greenspan may very well boost rates over the next few months if consumer spending revives or new-home sales explode again, as they did in July. Those who believe Greenspan would hold off on rate increases because of the presidential election should think again. He's a central banker first and a politician second.