In 1997, he changed professions, becoming a professor at Bentley College in Waltham.

While teaching at Bentley College, he travelled to Cuba for the first time in 1998 to study small business creation.

"The first time I came, I was hooked," he recalled. "I felt something in myself that I hadn't felt in a long time -- and that was that I could make a difference. Not a big difference, but a little difference in individual people's lives."

He turned to Rice, his long-time coworker, and together they began ETA. He was granted a "people to people" license -- a permit from the U.S. government that allows travel to Cuba for educational or cultural purposes -- and by 1999 he was bringing groups to Cuba regularly.

Through Consuelo Isaacson, president of Friends of Caritas Cubana in Boston, Eizenberg got to know Caritas Cubana. He now includes visits to Caritas Cubana projects on every one of his exchanges.

Bringing Americans to the Caritas Cubana sites are a "great way to bring the United States to the people of Cuba," so that they can make "personal connections" with individual people, he said.

"Cuba is unlike any other place we have taken anyone," added Rice. "You feel like you are really touching people's lives -- be it the tour guides, the waiters, everyone -- which is unlike anywhere else in the world since now society is so homogenized everywhere."

"By nature, the American people are very generous," added Eizenberg, noting that people who go on his exchanges often come laden with everything from soaps and spices to nail polish and children's toys -- items that can be found on any U.S. store shelf but can be nearly impossible to obtain for ordinary Cuban citizens.

Eizenberg noted that he has seen how the Cuban people have been changed by the donations they have received.

"It makes me feel very happy to see that they are starting to feel human again," he said.

For Eizenberg, the trips are also closely linked to his personal experiences.

He said the words of his mother, a survivor of a Nazi death camp, echo in his mind whenever he brings a group to Cuba.

"She used to say, 'We knew we were really in trouble when no one was coming (to Germany) anymore and we were left alone with them,'" said Eizenberg.

"I don't want that to happen to the Cuban people anymore," he added.

In the future Eizenberg is hoping to develop a campus ministry program facilitate student mission trips to Cuba.

"Campus ministries go everywhere in the world to help people, but they don't go to Cuba," he explained.

"We shouldn't keep Cuba off the map," he said.