She grabs my finger, spits on my blouse. A perfect guest with her dark eyes and flirty grin. Sophia, the daughter of my younger daughter, is a drooling, squirming, smiling, burping 2-month-old. It's Christmas and we gather in the living room next to the fire, with a tree in the corner, a snow village on the mantel, this real infant in my arms. Joy to the World! Peace on Earth!

Babies have a message for the rest of us. They are a symbol of hope. I look at Sophia and see endless possibility. With her goos and howls, she signals that it's time to begin again. This is the infant's gift to adults.

"Babies signify--well, you can get started all over again and change the things you did wrong," says Mary Ann Bartusis, a psychiatrist at the Veterans Affairs hospital in Las Vegas. "When you see a baby, it reminds you there is always hope--that there is going to be a better future."

Hope is the emotional commodity of the holiday season. Hope is also the mainstay of a healthy life. Study after study affirms the importance of hope in normal development.

There's research to show that hopeful people do better in school, compete more successfully in sports, handle more physical pain and recover more quickly from injuries and illness. At the University of Kansas, clinical psychologist C.R. Snyder is the author of "Psychology of Hope." He has devised a "hope scale"--a questionnaire of eight items--to assess a person's "hope IQ." The questionnaire includes such statements as "I meet goals that I set for myself," and "There are lots of ways around a problem."

Hope is not delusional, wishful thinking, says Snyder, but rather a mind-set that involves setting goals, devising strategies to achieve those goals and having the motivation to follow through.

Some of this is fancy psycho-talk for common sense. Setting goals is about finding meaning in life--in relationships, in the workplace, in the community, in the spiritual arena--and having the will and the way to get there.

What research has shown is just how important hope is. In a study of 200 students at the University of Kansas, for example, men and women who scored high on the hope scale ended up with better grades than those who scored low. In another study of people who suffered spinal cord injuries, those with high hope scores regained function more quickly, and if the injury resulted in paralysis, they were better able to set new goals. "Low-hope people don't seem to be able to do that," says Snyder. "High-hope people get going on another life."

Even in the treatment of mental illness where hopelessness is a feature of the disorder, finding hope is key to the recovery process. According to mental health researchers, people are born with the capacity to hope. A baby's smile reflects this basic instinct to hope. But emotional or physical suffering can cloud this natural capacity.

A person who is depressed, for example, is someone who feels hopeless; the pain of mental illness is so acute that it shuts down the ability to hope. Treatment may involve medication to relieve the pain and psychotherapy to build a meaningful life. "If we can alleviate their physical or emotional suffering, we can help them discover their own natural hopefulness," notes Washington psychiatrist Harvey L. Rich.

But sometimes the amount of suffering in the world seems overwhelming. Bullets rain on Chechnya, shells explode in an elementary school in the Middle East. Closer to home, an old friend is dying.

I look at Sophia, who gives me a gassy chortle. In her innocence, I see how vulnerable she is. My hopes for the future are tinged with the fear of all the things that can go wrong.

Fear not. That is the message of the season.

Dear Sophia, thank you for your gift of hope. I lean toward her basket. Her face goes scarlet and she produces a loud pooping noise, stopping all conversation. Her mother sweeps her up in her arms and heads for the diaper supply. All is Calm. All is Bright.