In retirement planning, financial advisers often talk to clients about a three-legged stool. It is an analogy for how to plan for our sunset years.

One leg of the stool represents retirement savings.

In the past, this meant a company pension. Now for many workers, it's a retirement plan they fund themselves, such as a 401(k).

The second leg represents personal savings, such as cash bank accounts or certificates of deposit. It might also include other assets, such as your home.

The third leg is Social Security, which provided at least half the income for 64 percent of seniors in 2006.

All three legs of the retirement stool are unstable.

And had we listened to President Bush and others, that last leg — the safety net that has kept millions of seniors, children and the disabled from poverty — would have been exposed to the recent turbulence and historic drops in the stock market.

Bush wanted to privatize Social Security by allowing younger workers to divert some portion of the payroll taxes into the stock market. One plan would have allowed people to invest in stocks, bonds or some mix of securities.

We, the people, Bush said, could invest our money and get a better return than the projected Social Security benefit checks.

But what if what we're going through is the Great Millennial Meltdown akin to the Great Depression? What if it takes 10 or 20 years for the stock market to recover?

In the last month, investors — many trying to fund their retirements — have lost, at least on paper, trillions of dollars. That retirement leg of the stool is looking pretty wobbly right now.

The national savings rate in America has been pitiful, dipping to negative territory two years ago. That leg of the stool has teetered for years.

The one leg that wasn't supposed to ever get rickety is Social Security. Yet the financial condition of the Social Security system remains problematic, according to the latest trustees' report.

"Social Security's current annual surpluses of tax income over expenditures will begin to decline in 2011 and then turn into rapidly growing deficits as the baby boom generation retires," the report said.

Growing annual deficits are projected to exhaust Social Security reserves in 2041.

What President Franklin D. Roosevelt said in 1935 when he signed the Social Security Act is still true today:

"The civilization of the past 100 years, with its startling industrial changes, has tended more and more to make life insecure. Young people have come to wonder what would be their lot when they came to old age. The man with a job has wondered how long the job would last."

Roosevelt understood that the government — we the people — needed to establish a net that was in place for times such as the one we're going through right now.

"We can never insure 100 percent of the population against 100 percent of the hazards and vicissitudes of life, but we have tried to frame a law which will give some measure of protection to the average citizen and to his family against the loss of a job and against poverty-ridden old age," Roosevelt said.

Then as now, we need an insurance fund in which we all share the risks and benefits. Social Security isn't just about you but about caring for the oldest among us and making sure they have enough money to at least pay for basic necessities. It's about insuring that the disabled who can't work have some income. Disabled workers and their dependents account for 16 percent of total benefits paid.

While we're fighting to stave off an economic depression, the looming Social Security crisis can't be ignored. But any change to shore up the system should also insure that one leg of the retirement stool is structurally strong and guaranteed to keep people from abject poverty.

E-mail Michelle Singletary at singletarym@washpost.com.