This is Hidden Brain. I'm Shankar Vedantam.

In the summer of 1776, 33-year-old Thomas Jefferson drafted one of the most important documents

in the history of the United States. The Declaration of Independence laid out a vision for a new country

and said all men had God-given rights to life, liberty, and the pursuit of happiness.

86 changes to the draft were made by John Adams, Ben Franklin, and others. Like many writers,

Thomas Jefferson is said to have been unhappy with the changes his editors recommended.

But the line about how we are all entitled to the pursuit of happiness endured.

In recent years, many elements of the Declaration of Independence have come under scrutiny,

including its omission of women, the poor, and enslaved people from its vision of equality.

We've examined some of these ideas in an earlier episode that looked at Thomas Jefferson's

complicated life story. This week on Hidden Brain, we launched a new series we're calling

Happiness 2.0. We start today by exploring Jefferson's psychological claim about what makes

for a good life, with research that examines what happens in our minds when we pursue happiness.

When you ask people what they want in life, nearly everyone will tell you they want to be happy.

After all, that's the point of finding a great job, starting a family, or going on wonderful

vacations. At the University of California Berkeley, psychologist Iris Moss studies a paradox

associated with our pursuit of happiness. Iris Moss, welcome to Hidden Brain.

Thank you so much for having me. Iris, about a decade ago, you achieved a major milestone

in the life of a scholar. You got 10 years at a great university. How long had you dreamed of

becoming a professor at a school like UC Berkeley? I think forever. So this was a really big deal for me.

I'd been working toward this for a long time and had been really looking forward to that moment,

hoping I would get 10 years. Getting 10 years is a big deal, of course. I would get to be with

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