“SoJo,” the cat of Representative Ayanna Pressley, Democrat of Massachusetts, is a celebrity in her own right. SoJo is a minor Twitter influencer; her appearance there wins likes and replies that include snapshots of admirers’ cats. Her popularity reflects how social media tastes lean toward cute pet clips and also speaks to me as a historian of black women’s politics. As Ms. Pressley explained, “SoJo” is short for Sojourner Truth Pressley Harris. Yes, Ms. Pressley’s pet carries the name of Sojourner Truth, one of early America’s best remembered African-American antislavery and women’s rights activists.

Truth knew that names tell a story, and so she changed hers. She was born enslaved in the 1790s, and, after her freedom in 1827, she changed her name from Isabella Van Wagenen, baptizing herself anew as Sojourner Truth. This started a life spent wandering in search of truths both religious and secular. Since then, black women have made sure that she is not forgotten, naming their clubs and schools for this foremother. They have sent her into the cosmos. In 1995, 13-year-old Valerie Ambroise, a student in Bridgeport, Conn., won the honor of naming NASA’s Mars rover with Sojourner: “She was a heroine to blacks, slaves and women. She acted on her strong feelings about life and the way it should be.” She added: “It’s only logical that the Pathfinder be named Sojourner, because she is on a journey to find truths about Mars.”

Naming is one essence of freedom. Some enslaved people resisted subjugation when naming their children; some changed their names, hoping to elude greedy owners and brutal slave catchers. With emancipation, many more threw off the names given to them by slaveholders, acquiring for the first time last names such as Freeman that passed on how it felt to savor the first moments of liberty. Even today, some of us carry the names of the families who called our forebears property. Also among us are those who are called by “X” and by unique names, signs of how the quest for freedom persists.