Howard Zinn, the Boston University historian and political activist who was an early opponent of US involvement in Vietnam and the author of the seminal A People’s History of the United States, died today at the age of 87 of a heart attack in Santa Monica, California. He was in a swimming pool doing laps and was spotted immediately by lifeguards but died instantly.

Zinn’s brand of history put common citizens at the center of the story and inspired generations of young activists and academics to remember that change is possible. As he wrote in his autobiography, You Can’t Be Neutral on a Moving Train (1994), “From the start, my teaching was infused with my own history. I would try to be fair to other points of view, but I wanted more than ‘objectivity’; I wanted students to leave my classes not just better informed, but more prepared to relinquish the safety of silence, more prepared to speak up, to act against injustice wherever they saw it. This, of course, was a recipe for trouble.”