The power of a positive thinker

But Seligman, the language quibbler, said he was rarely happy, as in joyful. It happened recently when one of his sons, a high school junior, pinned an opponent in wrestling. His happiest moment was the end of Game 6 of the 1980 World Series, when the Phillies won the championship. "That was the most joyous moment of my life, and I was very surprised by how I felt about it."

Seligman puts himself in the bottom 30 percent for positive emotions. "A life can be perfectly good and perfectly satisfactory with no positive feeling," he said.

That brings us to well-being, the subject of his next book and what matters to him now. Good feelings are part of it, but so are domains where Seligman thinks he excels. "My life is largely run around meaning and purpose now," he said.

And he is optimistic that his ideas can change the world. "That," he said, "is the point of it, as far as I'm concerned."

To read previous profiles in the Defining Lives series, go to http://go.philly.com/Defining_Lives

Contact staff writer Stacey Burling at 215-854-4944 or sburling@phillynews.com.