Watch This 'Market,' Too

It's not just the stock market that is floating down like a week-old helium balloon. Private charitable giving fell last year by 2.3 percent in the US.

And that's despite the largest single outpouring of charity in US history – $1.9 billion for Sept. 11 relief.

The biggest drop-off in giving was by corporations (14.5 percent), marking the end to a seven-year boom in corporate charity.

Yet despite the swift deflation in generosity, last year's giving by individual, companies, and foundations was the second highest on record ($212 billion, in inflation-adjusted dollars), according to a study by the Philanthropy Center at Indiana University.

It seems the spirit of philanthropy gets ever more enriched with each economic cycle.

Giving accounts for 1 percent of the US gross domestic product. In Europe, by contrast, giving accounts for between 0.2 and 0.8 percent of GDP. And the richest Americans usually start serious philanthropy when they've earned $20 million, compared with $100 million among Europeans.

Many financial advisers say that investors who commit to a greater cause through charitable contributions often feel focused and optimistic, and more easily ride out market downturns. Seeing the tangible returns of charity helps an investor feel more competent in picking financial securities that have real value.

And a new breed of high-tech donors has infused philanthropy with the same innovations and ideas that they use in their businesses. They want to put intellectual capital, not just money, into meeting human needs.

The level of giving is not just an economic indicator. It's an essential investment in the nation's prosperity.