Just after the 2004 Tsunami, I enjoyed lunch with friends in Jabiliya refugee camp in the northern Gaza strip. At that time, the camp was densely populated and deeply impoverished, often prone to flare-ups of excitement that could sometimes turn violent. After lunch, a bullhorn and a ringing bell from outside interrupted our chat. My ears pricked up, alert to any potential danger, but my host quickly resumed his relaxed posture. I inquired about the commotion. “Oh, they’re collecting for the victims of the big wave,” he told me. “It’s happening all over.”

I was — naively — astonished. Here were folks with almost nothing organizing on behalf of those with even less. Years later, I learned about a similar gift, collected by the Choctaw Nation, just after the Trail of Tears, for those facing famine in Ireland. The act is celebrated in the song by Irish singer and activist Damien Dempsey. “Choctaw Nation,” he sings, “I am in your debt. Chocktaw Nation, I just want to thank you.”

Solidarity as debt is a foundational frame for activists Leah Hunt-Hendrix and Astra Taylor in their book Solidarity: The Past, Present, and Future of a World-Changing Idea. One of the earliest instances of this idea is recorded in an ancient Hindu poem which states that “being born is a debt.” The first written mention of solidarity appears in Emperor Justinian’s legal code, which establishes a debt held in solidum as one held collectively. This means, for example, that if a group of farmers band together and one cannot pay rent due to illness or a bad crop, the others cover the debt.