LEWISBURG — The plight of the working poor and the widening gap between the very rich and the very poor were the dominant themes of best-selling author Barbara Ehrenreich’s “Working for Change: Citizenship and Class in America,” a speech she gave Monday night in the Weis Center for the Performing Arts on the Bucknell University campus.

“It is important to understand poverty through jobs and work,” she told the audience. “So when I first did undercover research for my book ‘Nickel and Dimed,’ I wanted to see if I could support myself as an entry-level worker at poverty-level wages. I was a waitress. I worked at a department store. I told no one who I was. I tried to see if I could live on a wage of $7 an hour. What I discovered was, it’s almost impossible to do so.”

Those on-the-job experiences led Ehrenreich to her theory that poverty is “not a character defect. Nor is it a lifestyle mistake.”

Poverty is caused by a shortage of money. It is caused by inadequate pay, she said.

Ehrenreich also believes that poverty does not exist in a vacuum. “It is the flip side of wealth at the top. It’s no coincidence that sales of private jets are at an all-time high at the same time that the working poor have to take buses to work and have two or three jobs. Or that cosmetic surgery is booming, while a significant portion of the population has no health insurance.”

What’s the answer? “Vote. But hold our leaders to their promises,” she said. “Our leaders will only be as good as we force them to be. We must organize around our shared vulnerabilities. This is what we have to do now, especially as our economy seems to be going under.”

The 40-minute talk was the latest in Bucknell’s national speaker series, “The Bucknell Forum: The Citizen & Politics in America.”