Sarah Lewis' grandfather was expelled from school for asking why his textbooks had no black people. Today she teaches at Harvard.

In 1926, Sarah Lewis’s grandfather, Shadrach Emmanuel Lee, was expelled from a Brooklyn public high school for asking why black people were not in his history textbook. His teacher told him African Americans had done nothing worthy of being included.

Last week, Lee’s granddaughter and some of her friends — among them Ava DuVernay, Wynton Marsalis, Henry Louis Gates Jr., Carrie Mae Weems, Theaster Gates, Bryan Stevenson, Naomi Wadler and Yara Shahidi — had Harvard University in their thrall.

Lewis teaches art history and African American studies at Harvard. She was the driving force behind “Vision and Justice,” a two-day convening focused on race and visibility sponsored by the Radcliffe Institute. The event, which coincided with a career-spanning Gordon Parks exhibition at Harvard’s Ethelbert Cooper Gallery (through July 19), will likely be remembered as a defining moment in the university’s history.

The star-studded cast addressed everything from algorithmic bias and the Flint, Mich., water crisis to the “adultification” of young African Americans and the human cost of mass incarceration. But the subject to which the speakers — who also included Chelsea Clinton, Teju Cole, Drew Gilpin Faust and David Adjaye — kept returning was visibility, and culture’s role in promoting it. As Lewis herself said: “You can’t fight the battle without pictures.”

“Frederick Douglass knew it long ago,” Lewis wrote recently: “Being seen accurately by the camera was a key to representational justice. He became the most photographed American man in the 19th century as a way to create a corrective image about race and American life.”